As said above, the lightest folding mobility scooter belongs to the TravelScoot company with the name of TravelScoot Deluxe.
It weighs just 35 lbs and is the most compact mobility scooter in the world. The heaviest piece is only 22 lbs.
With such weight, you can take it anywhere you want at any time. Even in a building with no elevator, you can carry the scooter without tiredness.