I would like to disable wall posts on my Facebook events to prevent people who aren't invited to the event from posting or even viewing the event's wall. Is it possible to disable an event's wall altogether?
There is no way to disable the events wall specifically (the comments section under the event description). But you can disable people who arent invited from seeing the event all together by setting the event privacy to to 'Invite Only'
From the Event Page: Edit -> Privacy: Invite Only (you can also tick the option to allow people who are invited to invite other friends if you wish)
It appears that if you turn of the RSVP option when creating an event it disables the standard members from being able to comment, but an admin can still comment on it.
As of now there is no other way to do this unless you do turn the RSVP option off. If you want it for whatever reason you will have to suck it up and delete any comments made.