To delete a user account off your Ubuntu server or desktop via terminal is pretty simple, thanks to the useful userdel command.

Given the username of the user account to delete, simply run:

sudo userdel -f usernametodelete

Of course, in the usual fashion of not giving you any feedback unless asked for it, the specified user account will be removed off the system.

To find out more of the switches available to you, refer to the man page:

man userdel

Simple and nifty.