diff --git a/app/services/destroy_task.rb b/app/services/destroy_task.rb
index e5ff8e5789c..b76d8f7f579 100644
--- a/app/services/destroy_task.rb
+++ b/app/services/destroy_task.rb
@@ -16,14 +16,13 @@ class DestroyTask
       topics = Topic.where(category_id: c.id, pinned_at: nil).where.not(user_id: -1)
     end
     @io.puts "There are #{topics.count} topics to delete in #{descriptive_slug} category"
-    topics.each do |topic|
+    topics.find_each do |topic|
       @io.puts "Deleting #{topic.slug}..."
       first_post = topic.ordered_posts.first
       if first_post.nil?
         return @io.puts "Topic.ordered_posts.first was nil"
       end
-      system_user = User.find(-1)
-      @io.puts PostDestroyer.new(system_user, first_post).destroy
+      @io.puts PostDestroyer.new(Discourse.system_user, first_post).destroy
     end
   end
 
@@ -36,11 +35,10 @@ class DestroyTask
       topics = Topic.where(category_id: c.id, pinned_at: nil).where.not(user_id: -1)
     end
     @io.puts "There are #{topics.count} topics to delete in #{c.slug} category"
-    topics.each do |topic|
+    topics.find_each do |topic|
       first_post = topic.ordered_posts.first
       return @io.puts "Topic.ordered_posts.first was nil for topic: #{topic.id}" if first_post.nil?
-      system_user = User.find(-1)
-      PostDestroyer.new(system_user, first_post).destroy
+      PostDestroyer.new(Discourse.system_user, first_post).destroy
     end
     topics = Topic.where(category_id: c.id, pinned_at: nil)
     @io.puts "There are #{topics.count} topics that could not be deleted in #{c.slug} category"
@@ -54,22 +52,19 @@ class DestroyTask
   end
 
   def destroy_private_messages
-    pms = Topic.where(archetype: "private_message")
-    current_user = User.find(-1) #system
-    pms.each do |pm|
+    Topic.where(archetype: "private_message").find_each do |pm|
       @io.puts "Destroying #{pm.slug} pm"
       first_post = pm.ordered_posts.first
-      @io.puts PostDestroyer.new(current_user, first_post).destroy
+      @io.puts PostDestroyer.new(Discourse.system_user, first_post).destroy
     end
   end
 
   def destroy_category(category_id, destroy_system_topics = false)
     c = Category.find_by_id(category_id)
     return @io.puts "A category with the id: #{category_id} could not be found" if c.nil?
-    subcategories = Category.where(parent_category_id: c.id).pluck(:id)
+    subcategories = Category.where(parent_category_id: c.id)
     @io.puts "There are #{subcategories.count} subcategories to delete" if subcategories
-    subcategories.each do |subcategory_id|
-      s = Category.find_by_id(subcategory_id)
+    subcategories.each do |s|
       category_topic_destroyer(s, destroy_system_topics)
     end
     category_topic_destroyer(c, destroy_system_topics)
@@ -84,14 +79,9 @@ class DestroyTask
   end
 
   def destroy_users
-    users = User.where(admin: false, id: 1..Float::INFINITY)
-    @io.puts "There are #{users.count} users to delete"
-    options = {}
-    options[:delete_posts] = true
-    current_user = User.find(-1) #system
-    users.each do |user|
+    User.human_users.where(admin: false).find_each do |user|
       begin
-        if UserDestroyer.new(current_user).destroy(user, options)
+        if UserDestroyer.new(Discourse.system_user).destroy(user, delete_posts: true)
           @io.puts "#{user.username} deleted"
         else
           @io.puts "#{user.username} not deleted"
@@ -121,7 +111,7 @@ class DestroyTask
   private
 
   def category_topic_destroyer(category, destroy_system_topics = false)
-    destroy_topics_log = destroy_topics_in_category(category.id, destroy_system_topics)
+    destroy_topics_in_category(category.id, destroy_system_topics)
     @io.puts "Destroying #{category.slug} category"
     category.destroy
   end
diff --git a/lib/tasks/categories.rake b/lib/tasks/categories.rake
index b2c9ab2c9f0..a3d58958929 100644
--- a/lib/tasks/categories.rake
+++ b/lib/tasks/categories.rake
@@ -39,8 +39,13 @@ end
 
 desc "Output a list of categories"
 task "categories:list" => :environment do
-  categories = Category.pluck(:id, :slug, :parent_category_id)
+  categories = Category.where(parent_category_id: nil).order(:slug).pluck(:id, :slug)
+  puts "id category-slug"
+  puts "-- -----------------"
   categories.each do |c|
-    puts "id: #{c[0]}, slug: #{c[1]}, parent: #{c[2]}"
+    puts "#{c[0]} #{c[1]}"
+    Category.where(parent_category_id: c[0]).order(:slug).pluck(:id, :slug).each do |s|
+      puts "     #{s[0]} #{s[1]}"
+    end
   end
 end
diff --git a/lib/tasks/destroy.rake b/lib/tasks/destroy.rake
index dd99bf52deb..d65a2039c38 100644
--- a/lib/tasks/destroy.rake
+++ b/lib/tasks/destroy.rake
@@ -4,47 +4,41 @@
 #   content and users from your site.
 desc "Remove all topics in a category"
 task "destroy:topics", [:category, :parent_category] => :environment do |t, args|
-  destroy_task = DestroyTask.new
   category = args[:category]
   parent_category = args[:parent_category]
   descriptive_slug = parent_category ? "#{parent_category}/#{category}" : category
   puts "Going to delete all topics in the #{descriptive_slug} category"
-  destroy_task.destroy_topics(category, parent_category)
+  DestroyTask.new.destroy_topics(category, parent_category)
 end
 
 desc "Remove all topics in all categories"
 task "destroy:topics_all_categories" => :environment do
-  destroy_task = DestroyTask.new
   puts "Going to delete all topics in all categories..."
-  puts log = destroy_task.destroy_topics_all_categories
+  DestroyTask.new.destroy_topics_all_categories
 end
 
 desc "Remove all private messages"
 task "destroy:private_messages" => :environment do
-  destroy_task = DestroyTask.new
   puts "Going to delete all private messages..."
-  puts log = destroy_task.destroy_private_messages
+  DestroyTask.new.destroy_private_messages
 end
 
 desc "Destroy all groups"
 task "destroy:groups" => :environment do
-  destroy_task = DestroyTask.new
   puts "Going to delete all non-default groups..."
-  puts log = destroy_task.destroy_groups
+  DestroyTask.new.destroy_groups
 end
 
 desc "Destroy all non-admin users"
 task "destroy:users" => :environment do
-  destroy_task = DestroyTask.new
   puts "Going to delete all non-admin users..."
-  puts log = destroy_task.destroy_users
+  DestroyTask.new.destroy_users
 end
 
 desc "Destroy site stats"
 task "destroy:stats" => :environment do
-  destroy_task = DestroyTask.new
   puts "Going to delete all site stats..."
-  destroy_task.destroy_stats
+  DestroyTask.new.destroy_stats
 end
 
 # Example: rake destroy:categories[28,29,44,85]