Ideally you would copy the backup as a separate named world just in case you don't want to revert. You can have both copies at once, under different names, with no problem. It's also best not to copy one world folder directly over another, or oddities can happen. Best to delete the one you want to copy over first, then copy the new one.
But again, for these purposes you really don't need to delete your current world unless you want to, just to get a backup back.