Try using a blow dryer or a heat gun on low and use a plastic putty knife gently scrape it while heating it up. Have a rag ready to wipe your putty knife off each time you make a scrape. Afterwards, try WD40 to get the remainder off.
Super hot soapy water and a trowel
Acetone, the kind you buy in the hardware store not nail polish remover.
Actually, we had to rent a floor sander from Home Depot to get the glue off. Thank you for your suggestion!