There are stopped jobs
% kill %3
to kill job number 3, which will cause it to exit prematurely.
If you get stuck or are in a hurry you can use the logout command twice in a row and you’ll be able to log out in spite of your stopped jobs. The jobs will be killed automatically by the shell. You really should clean them up yourself though.
If you have background jobs running (as opposed to stopped jobs) they will continue to run after you log out.