Occasionally, and especially on a new, out-of-the-box iRide scooter, the rear wheels do not rotate freely. Thee are two likely reasons for this:
1. It may be that the lock-down pins on the brakes have not been released. See page 23 of the owner's manual for details on how to do this
2. If the brake pin has been released and you're still experiencing the rubbing, it may be that the brake cables need adjusting just as they do on bicycles. Here's a drawing of what they look like. The easiest place to adjust them would be at point 'A'. You would loosen the locknut, screw the adjuster in until the brakes release and the wheels spin freely. Then tighten the lock nut. If that does not loosen the cable sufficiently, you can repeat the process right at each wheel at points 'B' and 'C' as shown on the drawing attached.