Having grown up driving tractors from 12 yo, there was a complete absence of presence of mind there. As others have said - push the clutch in and it would have solved itself.

What's causing it is that the tractor is rear wheel drive, so the drive in the rear wheels is what's causing it to lift.

Alternatively, reverse out.

Much like going up a steep hill, if you go up forward, most of the weight is at the back and it may raise at the front and flip. Instead, you can reverse up the hill, provided it isn't too steep.