Just unbolt the wing, and cut the third brake wire. Take a piec of Duct take and tape this on the insid so it doesn't flop around, and also incase you want to hook it up again. It would be best to have the hole welded, but it sounds like you want to use a plug. Go to a hardware store and get a couple different size plugs. I think 7/8 might fit for the wire hole(not sure about the bolt holes. but don't quote me. Make sure you get some sort of silicoln to seal the hole. Paint your plug and put some of the siloicoln on the inside lip-press into place. Remove any extra silicoln.
