If you are an AOP in a room, you can use services to deop people in the room who do not outrank you..
/msg chanserv deop #support webmaster
This should be used if someone was given ops and is misusing them. If the person is an AOP then if you are an SOP you should delete the entry to prevent them from reopping themselves. You will rarely want to deop someone who has the same status in the room as you do, since they can just reop themselves, and you can start a pointless struggle for control that no one can win. If you have problems with someone who has the same status, find someone of higher status in the room to deal with it. You might want to deop someone of the same status if he/she went away for a time and forgot to deop first.
Note: if you are opped and wish to deop yourself, you still need to be an AOP or higher to do it with services. But you can mode yourself -o in the room.