Burn your boats
To do something that makes it impossible for you to change your plans and go back to the situation you were in before.
She didn't want to burn her boats by asking for a divorce, so she suggested a trial separation instead.
I'd already burned my bridges with my previous employer by publicly criticizing their products.
Burn your bridges
To permanently and unpleasantly end your relationship with a person or organization.
Welles had burned his bridges so badly with the movie studios that they laughed when you mentioned his name.
Etymology: based on the military action of burning a bridge you have just crossed to prevent the enemy from crossing it after you