Don't have access to Delete files. HELP

My desktop are flooded with temporary files i save. Before I was able to delete them. Now it says I don't have permission to do so. It asks for my password, i was able to put my password since I'm the only person uses this laptop. When I do put the password it gives me this error message "The operation cannot be completed because you do not have sufficient privileges for some of the items. " It's weird because before I was able to delete files that are on my desktop, now I can't. But If there was a folder on the desktop and files in it, I can delete it but of course I cant delete that folder. And I cant rename them. Any suggestion on what to do or how to troubleshoot this?????