Removes privileges from or entirely deletes an entry in the
    Oracle Rdb access control list (ACL) for a database object. Each
    entry in an access control list consists of an identifier (or
    role) and a list of privileges assigned to the identifier.

    o  Each identifier specifies a user or a set of users.

    o  The list of privileges specifies which operations that user or
       user group can perform on the database, table, column, module,
       procedure, function or sequence.

    When a user tries to perform an operation on a database, SQL
    reads the associated ACL from top to bottom, comparing the
    identifier of the user with each entry. As soon as SQL finds the
    first match, it grants the rights listed in that entry and stops
    the search. All identifiers that do not match a previous entry
    are compared with the subsequent entry, and if no match occurs,
    they receive the rights of ("fall through" to) the entry [*,*],
    if it exists. If no entry has the user identifier [*,*], then
    unmatched user identifiers are denied all access to the database,
    table, or column. For this reason, both the entries and their
    order in the list are important.

    To create an entry or add privileges to an entry in the Oracle
    Rdb access control list for a database object, see the GRANT
    statement.