Username in already use

Do I have this right? When I make a new user, that name can never be created again even if I delete that user? I wish there was some warning about this. I was playing around with the VPS trial (which I still can’t get working) and deleted one of my users on my shared server, planning to recreate the user on the VPS. It’s not a huge loss, there was no data associated with the user, but I did plan on using it eventually.