To access the ignition switch, remove the steering wheel and combination switch.
Drill out the ignition switch mounting bolts or turn them out by turning with a chisel or punch.
You will need new shear bolts when installing.
Remove the ignition switch from the steering column and disconnect the connector from it.
Reinstall the ignition switch and secure with bolts. Connect the connector to the ignition switch, check the operation of the ignition switch and the steering lock. After checking their operation, tighten the bolts until their heads are sheared off.
Install the combination switch and steering wheel.