add reset smtp action

app/controllers/email_smtp_settings_controller.rb

@@ -3,7 +3,7 @@
 class EmailSmtpSettingsController < ApplicationController
   before_action :load_encrypted_config
   authorize_resource :encrypted_config, only: :index
-  authorize_resource :encrypted_config, parent: false, only: :create
+  authorize_resource :encrypted_config, parent: false, only: %i[create destroy]
 
   def index; end
 
@@ -23,6 +23,12 @@ class EmailSmtpSettingsController < ApplicationController
     render :index, status: :unprocessable_content
   end
 
+  def destroy
+    @encrypted_config.destroy!
+
+    redirect_to settings_email_index_path, notice: I18n.t('smtp_settings_have_been_reset')
+  end
+
   private
 
   def load_encrypted_config