How can I remove the airbag light from a 2015 Honda civic?

I disconnected the seat then turned on the car and now the airbag light is turned on.

Just put black tape over the light.

Go to a service center.

Gee, imagine that. Bypass the seat switch.

It is very hard.
Plug the seat back in.
Tampering with the airbag system in many locations is illegal.

The air bag light should go out if you didn't have a problem before disconnecting the seat wiring. The air bag system does a self check every time the motor is started and goes out if the system doesn't have any problems.
It's illegal to remove the air bag warning light. If you don't want to spend any money having the system codes read and the problem repaired just put a piece of black electrical tape over the light and wear your seat belt.

Hi so it is not just a case of removal of the light which indicates the air bag needs to be replaced. The body module will eventually force the car into limp home mode.

You need to ensure all plugs are plugged in, you may also may need to get the system reset. If the airbag light stays on or does not come on at all, that is an automatic MOT fail