Download & install the free Unlocker click here. Then right-click the file(s)/folder(s) that need deleting, select Unlocker & follow the wizard to delete.
Similar free programs click here, but I find Unlocker the best. G
P.S. Unlocker may come up as malware by your security program, but don't worry I've been using it for several years with no problems. It gets mistaken for another similar dangerous executable by the same name click here