Deleting a folder

Simple question I know, I see

 RMDir "$INSTDIR" 

being thrown around with or without the /r flag. I've placed a folder on the desktop and I was able to delete the files just fine. But I can't delete the directory. Also tried moving it with rename and whatnot but it doesn't seem to budge.

I set $INSTDIR as $DESKTOP/[folder name], and i checked to confirm it's the right directory with detailprint. But it won't budge. Need a bit of help with this issue.

Make sure your current $OUTDIR is not the directory you want to delete, or a sub-directory thereof.

Also make sure no other process is currently "locking" the directory...

And if all else fails, download Process Monitor from Microsoft and look at what is actually going on...