impact of employment location change

New employer is asking me to choose to work at:
company's Headquarter in state A
or company's regional office in state B
I'd like to work at the regional office in state B.

What happens to my EB-2 category greencard process if the new company later decides to close the regional office in state B, and asks me to relocate to the Headquarter in state B to do exactly the same job before I I-485 in state B (suppose my LC and I-140 filed in state B have already been approved).

Do I have to state over the whole greencard process if I am relocated to the Headquarter in state B? No exceptions?

Thanks for any comment.
Synthia