Its an easy process, and heres how to do it.
But if your theme is one you downloaded then it is already in your .themes folder.
Now open your file manager and navigate to your home folder then do to .themes folder.
Press Ctrl+H to enable it.
If you find it there then rename it to panel.rc.bak.
If you don’t find don’t panic!
Comment out this line by putting a hash mark # in front of it.
Now it should look like this # include “apps/gnome-panel.rc”
Save and exit the text editor.
Now change your theme to any other one then switch back to the one you edited.