kendall, did you forget the password on Ubuntu, for the user you had created? I think it must be for the user, since Ubuntu family does not require you to set the password for root while installation. I had installed Linux Mint and it had not asked to set the root password.
If that is the case, then as told by wdhpr, you can login as root with the password root, and then change the password for the user, by using the command :
passwd <username>
The password is case sensitive, and the username too. In Linux, things will always be case-sensitive.
I wrote the above steps assuming that you are still able to login to Ubuntu as root. If you are not able to login as root, then follow this link to reset your password :
http://www.psychocats.net/ubuntu/resetpassword
As for uninstalling Ubuntu, as wdhr said, you can just proceed with installing another Linux. Modern Linux installations detect already present OS, and act accordingly at the time of partition, so there should be no problem. Just install over the current Linux partition. Remember to backup your data on that partition, if any.