Question [Q] [Qhow to safely remove unncessary files on .Android secure


While doing a Nandroid backup I noticed that it took long time to backup the .android secure. So I check how big the files is and it's about 4GB!!!
I know that apps rely on .android secure so I can't just remove the files in a Helter-Skelter way and also when I goto .android secure I saw that there are files that is still there but it's apk is already uninstalled, a long time ago and I believe it's now a junk file but Junk cleaner like clean master don't do anything with .android secure. so... can someone guide me on how to delete unnecessary files on .android secure?