each network has there own varyation of services command
/ChanServ mDeop #Channel
is a command that could be used on the network i go to to solve this problem provided the person does not have any real access to the channel, if they actualy have access then the person needs to remove that access and then run this command
beings services differ however from one network to the next i strongly recomend you visit #services on your own network and discribe hte problem to them, hopefuly they will have a solution for you as i'd just be guessing at how your services are setup.
Cobra^