What do you mean by "older"?: That's the real question.

Do you want to delete files that have been sitting on the system for more than 5 days? Or do you want to delete files that were modified more than five days ago? Or do you want to delete files that were created more than five days ago?

You see, this isn't as simple as it seems, until you realize what you want. Unfortunately, most people here, and most people in general, will immediately assume that you are referring to modification time when you discuss a file's age, but that is not always the case.