Logins are used to access MS SQL server and to create DB users. You should create as many logins as many users you will have.
To create an MS SQL login:


Note: you can change password by clicking the Change icon against the login name in the Controls section.
To delete login, click the Trash icon against the login name, in the Controls section.
Important: With deleting a login, Parallels H-Sphere will delete all DBs created under it and also all users under the DBs. Also if you have some users under this login that are associated with another DB, these users will be deleted as well. Please make sure you want to delete the login before clicking Trash.