As indicated by the Department of Transportation, you can drop a non-refundable ticket and get a full discount of any airfare booked in the US without wiping out expenses and punishments as long as you booked the ticket 7 days in front of your flight and you demand the discount inside 24 hrs of booking. I would need to state Google flights are no special case.

Google don't sell the flights - they simply attach you with the carrier that does. Regardless of whether any given flight is refundable absolutely relies upon the terms and conditions related with the sort of ticket you purchase. So, enjoy your Google Flights Search experience