Removes this property from its parent group. If this is a property group, it removes the child properties as well.
This method is valid only for children of indexed groups; if it is not, or if the index value is not valid, the
method generates an exception and displays an error. (An indexed group has the type Proper-tyType.INDEXED_GROUP ; )
This method can be called on a text animation property (that is, any animator that has been set to a text layer).