dpending on what that person's done, thats how you'll remove them without nurting their feelings that much. Tell them why they are being removed. But dont just remove them witnhout a cleare reason....that would be hursh!
I gather this is a yahoo group. If you are the moderator go into the member list. You will see a box to the right of each member. Check that box to prepare to remove the member. Then go up to the top and click the "Remove Selected". The member will be removed and sent a message.