You need to create a custom forms designer for your component or control (make a class which inherits ComponentDesigner for non-visual components, ControlDesigner for standard components, ContainerControlDesigner for container controls, or ScrollableControlDesigner for container controls which support autoscrolling). In the class, override the PreFilterProperties method, and do this: Protected Overrides Sub PreFilterProperties(ByVal properties As System.Collections.IDictionary)
properties.Remove("MyProperty")
End SubThen, to set the designer to the appropriate control, give the <Designer(GetType(MyDesignerClass))> _ to your control (replace MyDesignerClass with the name of the designer you created) and all should be well.
At that point you can redefine the property yourself and set its Browsable attribute to false.