The CHECK_POLICY and CHECK_EXPIRATION options cannot be turned OFF when MUST_CHANGE is ON.

 

1. In the below step I am giving the same password, to fix “User Must Change Password” flag.

 

USE Master

GO

ALTER LOGIN [Login Name] WITH PASSWORD = 'Same Password'

GO

2. Turnoff the passowrd policy

 

ALTER LOGIN [Login Name] WITH

CHECK_POLICY = OFF,

CHECK_EXPIRATION = OFF;

Refer to: