Removing an ignition-lock cylinder is usually only possible with the ignition key. However, in a pinch, you can drill the lock out. This should only be used as a last resort, since you can permanently damage delicate components behind the cylinder. If the ignition switch and lock cylinder are separate components, there is a risk that you will destroy the ignition switch along with the lock cylinder.
Test fit a drill bit in the lock cylinder. You want a bit that is just smaller than the cylinder. You will be using hardened drill bits to cut through the cylinder, since ordinary bits may be damaged by drilling metal.
Lock the drill bit into the drill chuck and tighten the chuck.
Drill a starter groove into the lock cylinder. Start the drill on a low speed and create a groove in the end of the lock cylinder. You don't need to create a deep hole, just enough of a groove so that the drill bit will not slip on a higher speed.
Increase the drill speed to the highest setting and drill out the lock cylinder. Let the drill do the work. If you force the drill into the lock cylinder, you could burn out the rotor inside the drill motor.