Really need to remove the wheel in order to reach the ignition lock?
Maybe removing the garnish from the steering column might do the trick. I don't know much about Coronas but in 70's Celicas it's screwed from below.
If you have to remove the wheel:
1. Carefully remove steering wheel center emblem with a screwdriver
2. Release nut that holds wheel on steering column
3. Pull wheel
If the wheel is on there for a couple of years you might need a pulling tool. Or you should let the nut untightened on the bolt when you start beating the wheel from behind in order to keep it out of your face.