Hello this is really easy to do with BMW-scanner (PA Soft) and a laptop.
Just disconnect those airbags you dont want to have and uncheck them in the program under SRS/Coding data/Equipment.
The hardware can be bought anywhere, for example
https://www.amazon.com/Aidixun-obd2-...3476247&sr=8-6
It can also be done, a little bit mor tricky, with NCS-Expert which is included in the Inpa Ediabas Suite.