How d I fix the "beeper" that sounds when the door is open too long

Disconnect the beeper speaker or muffle the speaker sound with something like tape across it.

I suspect that the Logic Control Board is shot. If the unit is 1 year old or less try:

In the U.S.A., warranty is offered by Sunbeam Products, Inc., located in Boca Raton,Florida 33431. 1.800.334.0759
In Canada, this warranty is offered by Sunbeam Corporation (Canada) Limited,located at 5975 Falbourne Street, Mississauga, Ontario L5R 3V8

To refresh, the beeper should sound once. The definition of the Beeper from the manual follows:
BEEPERFUNCTION
(1) When you plug the unit in, the beeper sounds once and " - - - "appears in the LCD.
(2) When you press one of the four menu buttons the beeper will sound one time.
(3) When you press the adjustable button, every time you press the button, the beeper
will sound once. If you press the button continually, the beeper only sounds one time.
(4) When you press the start button the beeper will sound once, and ":" will flash, that means
the unit is in operation. Once the unit has begun the cooking cycle, the menu selection,
time or temperature cannot be changed. The unit must be stopped and reset.
(5) When the unit is in operation, press the stop button, the beeper will sound once and the unit
will stop operation.
(6) At the end of pre-set time, the unit will sound a long beep to remind you the work is done.

you can remove the switch for the drivers door and tape the plug then cover the hole. its located right below the latch the on door opening

Try resetting the computer. Take the negative battery cable off, wait 5-10 minutes then put it back on.

The alarm system is integrated into the vehicle electronics, you can't completely bypass it. You don't need a remote to have it work right and not go off, you have a problem with the system like a door sensor.

Check the little switches in the door ...there is a sensor thats like a push button..if that broke off it will always think your door is open..you may need to replace..

you should start by checking fuses,switch located on door pillar where door hinges are.sounds like a blown fuse or bad beeper,

Try pressing the cut off button manually while the door is open. It sounds like the switch may be bad.

I suppose you mean beeper does not go "on" when head lights are "on" and you open drivers door.In this case beeper's door switch may be dirty. Check also for any loose wire connection or faulty beeper relay.

I have Kenmore microwave model 721.61820100.
It has an "Option" button. Press it. The display say "NUMBER"
Then press "1". The display should say "SOUND" and then "OFF".
Press "Start" and that beast turns silent, well not really, but the beeps are goooone.

If for some reason you don't like it this way repeat the sequence and the sound this time will turn "ON".