Clear a relation (or all relations) held by this server to other servers.
METHOD ClearRelation( nRelation )
nRelation The number of the relation to clear. If omitted, all relations are cleared.
LOGIC TRUE if successful; otherwise, it returns FALSE.
The server will send a NOTIFYCLEARRELATION to the child/children. This will automatically reset the children to show all records and will send a NOTIFYRELATIONCHANGE to all their children.