How do i find movies that have been decrypted? I don't know where to look for them on window vista.?

I have decrypted some movies. I want to go back and delete them off my computer, so I do not lose too much space on my computer. I do not know where to look for them. I do not know how to delete them once I find them. I need to know how to take music off after I make a cd. I am computer illiterate. Please help me?