Assuming you are the owner, I would suggest putting the bike on a center stand or paddock stand, then placing a small jack under the exhaust to lift the front wheel of the ground (just so the wheel is not touching the ground, not very high). This means there is now no weight on the front wheel and I would remove the top yoke, it's quite easy, just loosen the 2 fork clamp pinch bolts on the top yoke, remove the large center steering stem nut and you should be able to lift the top yoke off the bike. If you then disconnect the wiring lead from the ignition switch, you should have access to the bolts on the underneath of the top yoke that mount the ignition switch to the yoke. You can then drill the 2 bolts out, or go to a machine shop and have then remove the 2 bolts. Fit a new ignition switch and put the top yoke back on and you should be good to go. The new switch will now have a different key, but it's usually the easiest way to fix this.
Hope that helps.