Removes privileges from the Oracle Rdb access control list
    granted by a specific user for a database object. Each entry in
    an ANSI/ISO-style access privilege set consists of an identifier
    and a list of privileges assigned to the identifier.

    o  Each identifier specifies a user or the PUBLIC keyword.

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

    For ANSI/ISO-style databases, the access privilege set is not
    order-dependent. The user matches the entry in the access
    privilege set, receives whatever privileges have been granted
    on the database object and receives the privileges defined for
    PUBLIC. A user without an entry in the access privilege set
    receives only the privileges defined for PUBLIC. The PUBLIC
    identifier always has an entry in the access control list, even
    if PUBLIC has no access to the database object.

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