diff --git a/lib/plugin/instance.rb b/lib/plugin/instance.rb
index 50867afaa0e..168c3a36c65 100644
--- a/lib/plugin/instance.rb
+++ b/lib/plugin/instance.rb
@@ -2,7 +2,6 @@ require 'digest/sha1'
 require 'fileutils'
 require_dependency 'plugin/metadata'
 require_dependency 'plugin/auth_provider'
-require_dependency 'plugin/theme'
 
 class Plugin::CustomEmoji
   def self.cache_key
@@ -74,6 +73,19 @@ class Plugin::Instance
 
   delegate :name, to: :metadata
 
+  def serve_public_dir
+    public_dir = "#{directory}/public"
+    if File.exist?(public_dir)
+      Rails.application.config.before_initialize do |app|
+        app.middleware.insert_before(
+          ::Rack::Runtime,
+          ::ActionDispatch::Static,
+          public_dir
+        )
+      end
+    end
+  end
+
   def add_to_serializer(serializer, attr, define_include_method = true, &block)
     klass = "#{serializer.to_s.classify}Serializer".constantize rescue "#{serializer.to_s}Serializer".constantize
 
@@ -259,14 +271,6 @@ class Plugin::Instance
     Plugin::CustomEmoji.register(name, url)
   end
 
-  def register_theme(name)
-    return unless enabled?
-
-    theme = Plugin::Theme.new(self, name)
-    yield theme
-    themes << theme
-  end
-
   def automatic_assets
     css = styles.join("\n")
     js = javascripts.join("\n")
diff --git a/lib/plugin/theme.rb b/lib/plugin/theme.rb
deleted file mode 100644
index 41ba7dc9992..00000000000
--- a/lib/plugin/theme.rb
+++ /dev/null
@@ -1,29 +0,0 @@
-class Plugin::Theme
-  attr_reader :color_scheme
-
-  def initialize(plugin, name)
-    @plugin = plugin
-    @name = name
-  end
-
-  def css(name)
-    @plugin.register_asset("stylesheets/#{name}.scss")
-  end
-
-  def set_color_scheme(scheme)
-    @color_scheme = scheme
-  end
-
-  def register_public
-    public_dir = "#{@plugin.directory}/public"
-    if File.exist?(public_dir)
-      Rails.application.config.before_initialize do |app|
-        app.middleware.insert_before(
-          ::Rack::Runtime,
-          ::ActionDispatch::Static,
-          public_dir
-        )
-      end
-    end
-  end
-end