You can deny a user or user group access to a database
by removing their subscription to that database.
About this task
Attention: If a user is a member of a group that
is subscribed to a user database, then the user can log on to the
database even if they are not a direct subscriber. To unsubscribe
a user to a database, you must remove that user from all the groups
that are subscribed to the database.
To
unsubscribe users or user groups to databases: