It has been asked several times in this forum about disabling airbags because of aftermarket seats, so I'll post this here.
Check for local regulations before performing any deactivation/reactivation. For example, Germany requires that this must be checked by an authorized test center and entry made in the vehicle documents.
This information is shared for persons working on cars and need to temporarily disable the airbags, or others with a need to do so (e.g. frequently carrying a small child in the front passenger seat). The airbags are there for safety, I recommend that they normally be enabled.
Note: this description is based on using VAG-COM from Ross-Tech and having prior experience using it. If using anything else you will have to adapt the instructions.
1) determine if your car can do this. Use VAG-COM (or equivalent) to access the airbag controller. Look at the Component box in the upper right corner. In the middle of the string you should see 'VWx' where x is a number. This number must be 5 or higher. Anything lower requires a special resistance kit installation (1J0 998 521). An exception to this is VW3 with part number 1J0 909 609. This controller does not require the resistance connector.
2) Click on 10-Adaptation
3) Click up for the channel number to get to channel 01. This is the passenger front airbag channel. The value is 0 (zero) for 'enabled'. Click the up arrow to make it a '1'. Click 'Save' and confirm the prompt. This will disable that airbag.
For the other airbags, disabling them is a matter of choosing a different channel.
1 - passenger front
2 - driver front (steering wheel)
3 - passenger side (seat airbag)
4 - driver side
5 - passenger belt tensioner
6 - driver belt tensioner
7 - passenger head
8 - driver head
Enabling the airbag is just a matter of performing the same steps but decrementing the channel value from 1 to 0.
When an airbag is disabled, the airbag light will light on the cluster for the normal 4 seconds when you first turn the starter key to the on position, then additionally flash for 12 seconds.