File deletion

I created a couple of forms where one inserts new contact data with a file, in this case its a resume. Now, I want to create a form where a user can update the information by inserting their updated information and if there is a new resume then it would be uploaded. I got the upload part down, but i would like to delete the old resume when the update is done, only if there is an update done to the resume. This more for file management than anything. I am sure this is possible, but I thought I would ask all you PHP experts first since I am a semi-newbie at this... thanks!