From Tapestries MUCK
This function will remove a property and all of it's subsidiary properties in the case that it is a propdir. This will delete the property on the trigger object, unless an object argument is specified. If one is, then it will delete the property on that given object.
This function returns a null string.
If you specify a propname that is protected, you will get an error of Permission Denied. You are only allowed to delete properties from objects that are owned by the owner of the trigger object.