Where can you buy the steering wheel for a 1990 Oldsmobile Delta 88?
Try going to "autoaccessories4less.com.
this is not for a novice, especially if you car is equipped with tilt steering, but can be accomplished if you follow the instructions on the repair guide that comes with the new ignition lock cylinder ( make sure when purchasing that they are included). you may need to buy / rent a spring compressor kit, especially made for small springs, and a steering wheel puller.
If it has an air bag, don't do it yourself. Take it to someone who is trained since those things can go off and cause serious injury. If it DOESN'T have an air bag: Disconnect the battery. Remove the screws from the back of the steering wheel that hold the horn assembly down. Remove the horn switch assembly. Remove the center nut. use a steering wheel puller to pull the steering wheel off the shaft.
Do not do this during an electrical storm. Disconnect negative battery cable. Wait 10 minutes. Remove the bolts holding the airbag bodule/horn pad to the steering wheel (from the back.) Hold the airbag module with one hand, then with the other hand unplug the horn wire and airbag wire. Move the airbag module away from the car. Set it down someplace out of the way and face up where other people won't go near it…