That happens when you change the db owner.

What does this return:

SELECT SUSER_SNAME(owner_sid)

FROM sys.databases

WHERE name = 'yourDatabase';

I think you'll find that it returns CUSTOMERCARE\dscott, which is probably the person who created the database. By default the db creator is made to be the owner.

Change the DB owner and then I think you'll be able to drop the login. I default to having all my databases owned by sa unless I have a specific security requirement that compels me to use a different login.

ALTER AUTHORIZATION ON DATABASE::yourDatabase TO sa;