In the Administrator tab of the Project Security, you can change the default credentials and a user role for the Administrator user:
2 Administrator Properties
In the Administrator tab the following properties are available:
2.1 User Name
The user name is used to log into the application as the Administrator.
Default value: MxAdmin
The password is used to log into the application as the Administrator. Click Show password to see the password.
Default value: 1
2.3 User Role
The user role assigned to the Administrator. For more information, see User Roles.
Default value: Administrator
The administrator is always created and has the System.Administrator role by default. The System.Administrator role allows users of your application to be managed. On sandboxes the user that created the application automatically has this role by default as well so you can use it to manage your users in that environment. This role may be helpful in case you have exceeded your user license restriction in which case you can use any user that has this System.Administrator role to login to manage your users.