404 file not found error on client's server while deleti

Hello
I am getting 404 file not found error while deleting user in backend on client's server. In error log we found that it is looking for 
/Sitefinity/WebsiteTemplates/MyTemplate/App_Themes/ThemeMaster/Styles/MenuMoreActions.css  file which is not present in my theme. 
On local server it is working fine.  We can not upgrade the site now as it is delivered to client.
Please help me.