You can delete an email address from all VPOP3 distribution & mailing lists.

Go to Settings → Database → Query

Alternatively, at a command prompt in the VPOP3 directory run

psql

(The password is 'vpop3pass')

Then, type

DELETE FROM users.listmembers WHERE LOWER(address)='<email address in lower case>';

Replace <email address in lower case> with the full email address in lower case.

N.B. VPOP3 does not need to be stopped while you do this