Fly it.
This is an issue that only happens on the ground because the controller is trying to adjust the level by increasing a motor, but it doesn't help because the motor doesn't have enough thrust to actually lift that corner off the ground.
Beware: Don't let it do this speedup a long time and then try to lift off. It tries harder and harder to make it level, so that motor is running a lot faster. When you lift off, it will try to flip over because that motor is too fast.
When you get ready for your first flight, Arm and quickly increase throttle until it is hovering at about knee high to chest high. If you are worried about it being set up correctly (I guess you should be
), and are willing to accept the risk, get out your old winter coat and put it on for arm protection, then carefully hover while holding it with your hand. It should fight you to stay level. A little bit of roll/pitch on the transmitter (careful not to steer it into your arm) should change the bank angle. Note that yaw (rudder) is very weak and you will either have to rotate it by hand so that all motors are about the same, or loosen you grip enough that you can feel it moving in the desired direction. The desired direction is the direction it was pointing when the motors were started.