burn (one's) bridges
To eliminate the possibility of return or retreat

[TahlilGaran] Dictionary of Contemporary English ▲

burn bridges
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

[TahlilGaran] English Idioms Dictionary ▲

burn one's bridges
v. phr. To make a decision that you cannot change; remove or destroy all the ways you can get back out of a place you have got into on purpose; leave yourself no way to escape a position.
Bob was a good wrestler but a poor boxer. He burned his boats by letting Mickey choose how they would fight.
When Dorothy became a nun, she burned her bridges behind her.

[TahlilGaran] English Idioms Dictionary ▲