From Xojo Documentation
Removes an event handler that was added by AddHandler. You need to match the AddHandler call.
RemoveHandler <event> , <method>
|eventName||The event is handled by a method.|
|delegateMethod||The method that handles the event.|
Always remove any handlers added with AddHandler when you are finished with them.
This example removes the work of the AddHandler example. Please see that example for a description of how it works.
This removes the handler that was added by the example in AddHandler.