sp_drop_and_recreate_user.sql

CREATE PROCEDURE dbo.USP_DROPANDRECREATEUSER
    (@username VARCHAR(100),
	@domain varchar(100))
AS
    BEGIN
		DECLARE @loginName VARCHAR(200) = @domain + '\' + @username;
       
        DECLARE @script VARCHAR(MAX);
        IF EXISTS (SELECT 1 FROM sys.database_principals AS s WHERE  s.name = @username)
            BEGIN
                PRINT 'Dropping USER ' + @username + '.';
                SET @script = 'DROP USER ' + @username;
                EXEC (@script);
            END;
        PRINT 'Creating USER ' + @username + '.';
        SET @script = 'CREATE USER [' + @username + '] FOR LOGIN [' + @loginName + '];';
        EXEC (@script);
    END;

this can be handy when using ssdt projects. if your users domain name vary across environments, you cannot create the user as a part of the ssdt project. It should be created via postdeploy script. From postdeploy script, call this stored proc.