you cant
dampen a rag with lighter fluid or mineral spirits. no you wont remove the polyurethane, its dry. but it will however remove the glue with no problem or blemishes in your poly.
Cant be done sorry
Hammer and chisel to scrape it off, an assortment of putty knives.
My man installs floors. He said Mineral Spirits will remove any residue without damaging your new finish.