I have this brushmodel in my map that I would like to remove but for some reason I cannot select it. I've tried selecting it from many different angles but it just selects the stuff behind/below it. Any help?

Make a brush touching it and use select touching.

Thanks man +1

Do you know why this happens in the first place?

Not sure, but I've had un-select-able brushes in my map before.

Happens to me, when classname has typo in it or its wrong regarding what the actual thing is