Hang on a moment; depending on the situation where you do this, you might be removing a whole lot of eventhandlers that you shouldn't be removing. You want "removeEventHandler _id", which will remove a certain e-h but not all of them.
It's been a while since I last used e-h's, or user-added actions, but there is a trick (check the comref) which makes it easier to track ids for actions; you could say
_myAction = player addaction ["Hello","Hello.sqs"]
which would set the variable _myAction equal to the index of the new action. Then you could say
removeaction _myAction
to remove the correct action.
Presumably the same applies to eventhandlers, if so this is a much better way of managing them