Tables=(table-list)

    Specifies the table or tables for which column group entries are
    to be deleted, as follows:

    o  If you specify the Tables=(table-list) qualifier, but do
       not specify the Column_Group qualifier, then all column
       group entries for the listed tables are deleted from the
       RDB$WORKLOAD system table.

    o  If you specify the Tables=(table-list) qualifier, and you
       specify the Column_Group=(column-list) qualifier, then the
       workload statistics entries for the specified tables that
       have exactly the specified column group are deleted from the
       RDB$WORKLOAD system table.

    o  If you use an asterisk (*) with the Tables qualifier
       (Tables=*), all tables registered in the RDB$WORKLOAD table
       are deleted. This allows the RDB$WORKLOAD table to be purged.

    If you issue an RMU Collect Optimizer_Statistics command after
    you have deleted a workload column group from the RDB$WORKLOAD
    system table, those statistics are no longer collected.

    The Tables=(table-list) qualifier is a required qualifier; you
    cannot issue an RMU Delete Optimizer_Statistics command without
    the Tables=(table-list) qualifier.