Remove the two wires going to the horn...

...let them dangle anywhere, as long as you don't press the horn button nothing will short.

Use the 12 and 13 mm wrenches to remove the nut and washer securing the bolt which holds the horn.

Slide the bolt back toward the front fender while holding the horn so it does not fall. Carefully remove the horn so as to not damage the front fender paint. Place the nut and washer back on the bolt in the frame so they don't get lost.

Installation is the reverse.