I think at that rate there isn’t a bad decision. Pay it off for the peace of mind. Or, if you have a higher risk tolerance, invest it in the market, since long term it would likely return more than 4.5% (historically speaking, of course). I think keeping the money to keep it in a money market account or CD is probably not worth it, though.
Another thing is that if for whatever reason you need that money you still have acess to it, but if you pay off your loans, you can’t easily get it back.