According to the general principles of civil law, it is an alterable and revocable act, but you have to go to court to sue and apply to the court for change or revocation.

Revocable civil act (meaning defective):

1, major misunderstanding (both parties have the right to cancel).

2. Obviously unfair (both parties have the right to cancel).

3, fraud, coercion, taking advantage of the danger of others (the injured party has the right to revoke) but did not harm the national interests or social public interests.