To change your character's name, simply follow these steps:
Start up Ultima Online with the character you'd like to change name on.
Double-click on the token and you'll be presented with a window that will ask you to enter your character's new name.
NOTE - There are a couple of restrictions that you should keep in mind:
A character's name can only be changed ONE TIME every 24 HOURS.
Enter the new name of your choosing and click "OK".
If the name entered is not a valid name, the text in the Name Entry box will disappear. Please enter a valid name.