Only way i see is to warn house owner to shut the rest of house off , use an angle grinder with diamond blade for little corners and a skill saw style cutter set height so it does not cut all the way through. Once you have an edge open, use a large hand chisel , 4 inch across and smack it under to chip large sections off. Lots of cuts in the top. this worked for me, but major mess dust every where. The glue cleans up easy with the right type of fitting on angle grinder.