On these port expanders, there are internal pull-ups permanently enabled (and secondary ones transiently enabled if you write the port HIGH). So they default to "1" and you do not need to connect them to anything if not needed. 
On these port expanders, there are internal pull-ups permanently enabled (and secondary ones transiently enabled if you write the port HIGH). So they default to "1" and you do not need to connect them to anything if not needed.