An internal auditor at a bank informed the branch manager of a malfunctioning lock on...

Inform senior management that the branch manager deeded to cancel the committed action plan without any previous communication

Discuss the issue with the board which has ultimate responsibility to resolve the risk

Have another discussion with the branch manager attempt to change his view, and encourage him to movement the recommendations

Document the branch manager's decision to accept the risk otherwise, no other speak: course of action is required.