Viewing and Modifying Role Memberships
While using a database, you may need to list the members of a database role or fixed server role. Or, when a Microsoft® SQL Server™ user no longer needs the permissions from a user-defined, fixed database or server role of which she is a member, you may want to remove the user from the role to keep the security system as simple as possible.
To view the members of a database role
Transact-SQL