Greetings Robert,
Since the tree has been removed, there is no reason now why you can't excavate the roots that are surfacing. Furthermore, you may want to apply herbicide such as Pathway (active ingredient Picloram) or Garlon (active ingredient Triclopyr) to effectively kill the rooting system of this silver maple. Neither of these herbicides will kill the adjacent grass as they are broadleaf/woody specific. Furthermore, do not use the Pathway herbicide if there are other silver maples /red maples on this property or adjacent to this property that may be root grafted.
As with all herbicides, the landowner must read and follow the herbicides label to ensure proper rates and handling. The University of Illinois assumes no liability for misapplications or improper use of herbicide.