This recipe answers the question, How do I make sure that user X cannot access table Y?
The current user must either be a superuser, the owner of the table, or a user with a GRANT option for the table.
Also, bear in mind that you can't revoke rights from a user who is a superuser.
To revoke all rights on the table1 table from the user2 user, you must run the following SQL command:
REVOKE ALL ON table1 FROM user2;
However, if user2 has been granted another role that gives them some rights on table1, say...