Facebook Events – No ‘Going’ Button Available

Actually, there is a way to remove an event. You have first to join or decline, then you click on the "going" list or "Maybe" list. You'll find yourself & a small "x" next to it. Click "x" to remove the event.

If you select the "maybe going" option, it shouldnt show up in your friends newsfeeds. And if you want the organiser to definitely know you are going, you could send a private message to the organiser, that also wont show up in your friends newsfeeds.

UPDATE Facebook have changed things now, and have added a third option of "interested in" event. For public events this has replaced the "maybe" option, but stories about you selecting the "interested in an event" option do now get broadcasted to your friends. For private events, they still have the "maybe" option which works the same way as it used to.