AddHandler o.Validating, New System.ComponentModel.CancelEventHandler(AddressOf OnValidating)
AddHandler o.Validating, AddressOf Me.RoutineName>Answering #1 certainly answers this one, so I only need comments if you feel its necessary:
RemoveHandler o.Validating, New System.ComponentModel.CancelEventHandler(AddressOf OnValidating)
RemoveHandler o.Validating, AddressOf Me.RoutineNameHope that helps...