While 'Bonanza' is a natural genetic dwarf, it's often grafted to Lovell understock because of Lovell's ability to adapt to a wider variety of soils. Since the top is clearly viable, I would rub off any/all branch buds as they occur on the trunk proximal to the lowest conspicuous branches, just to be safe and to prevent the understock from sapping resources from the scion or taking off on it's own, to the demise of the scion.
Al
