You should not get any errors deleting UI files when the game is not running. For that matter, you should be able to delete anything in the EQ2 folder as long as the game isn't running. If you do, then the error is actually that the OS is marking files as in use when they aren't. This does happen from time to time and there's no way to tell from this distance what might have caused it.
Try this: restart your system. Next, try to delete the ProfitUI folder. Don't do anything else in between. If the system complains that the folder is in use, then you have a 'stuck' folder. Fixing that is a different issue.
-= Therendil =-
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