It's in the owner's manual. This is from my 2003 F2:
One time disable
Any time the safety belt is buckled and then unbuckled during an
ignition ON cycle, the BeltMinder will be disabled for that ignition cycle
Deactivating/activating the BeltMinder feature
Read steps 1 - 9 thoroughly before proceeding with the
deactivation/activation programming procedure.
The BeltMinder feature can be deactivated/activated by performing the following procedure:
Before following the procedure, ensure that the following conditions are met:
The parking brake is set.
The gearshift is in P (Park) (automatic transmission) or the neutral position (manual transmission).
The ignition switch is in the OFF position.
All vehicle doors are closed.
The drivers safety belt is unbuckled.
The parklamps/headlamps are in OFF position (If vehicle is equipped with Autolamps, this will not affect the procedure).
To reduce the risk of injury, do not deactivate/activate the Belt
Minder feature while driving the vehicle.
BeltMinder activation and deactivation procedure
1. Turn the ignition switch to the RUN (or ON) position. (DO NOT
START THE ENGINE.)
2. Wait until the safety belt warning light turns off. (Approximately 12 minutes.)
Steps 35 must be completed within 60 seconds or the procedure will have to be repeated.
3. Buckle then unbuckle the safety belt three times, ending with the safety belt unbuckled. This can be done before or during BeltMinder warning activation.
4. Turn on the parklamps/headlamps, turn off the parklamps/headlamps.
5. Buckle then unbuckle the safety belt three times, ending with the safety belt unbuckled.
After step 5 the safety belt warning light will be turned on for three seconds.
6. Within seven seconds of the safety belt warning light turning off, buckle then unbuckle the safety belt.
This will disable BeltMinder if it is currently enabled, or enable
BeltMinder if it is currently disabled.
7. Confirmation of disabling BeltMinder is provided by the safety belt warning light flashing four times per second for three seconds.
8. Confirmation of enabling BeltMinder is provided by:
The safety belt warning light flashing four times per second for three seconds.
Followed by three seconds with the safety belt warning light off.
Once again, the safety belt warning light will flash four times per
second for three seconds.
9. After receiving confirmation, the deactivation/activation procedure is complete.
Originally posted by jefff I cut the wire located in the cable for the drivers seatbelt.
According to the shop manual section 501-20B, some vehicles have "pre-tensioners" integrated in the seat belt buckles. They take out the slack in the event of an accident when the SRS deploys. They are like the airbags and are a percussion system. I would be careful about cutting any wires, something may go boom.