How do you reset a stereo in a 93 BMW?

Unbolt the radio, there are two little tabs on each end of the face of the radio. a small "pocket screw driver" ill pop them open. you'll see the tabs where you insert the screw driver. once those are popped open, then you will have acess to Allen bolts. one per side. unscrew each bolt (they wont come out of the radio, they just loosen). now, pull the radio out. I usually just pull via the tape deck slot. once its pulled out of the dash, write down the serial number stamped in the steel on the back. you do not have to unplug the radio, just write down the serial number. Go into your local BMW dealer and they can look up the serial and give you a radio code. the radio code i believe is 6 digits. turn the radio on, it will say "radio code". punch in the number code from the dealer. the radio will then become availble for regular use. if you punch in the number wrong too many times, the radio will be locked out, and you must leave the car running for 1-1.5 hours before it will release its self and allow you to attempt to enter the radio code again.