It may be a grafted or bud grafted tree so if you cut it down to 19 or 20 inches (.5 meter) you may cut below the graft or the bud grafts. Otherwise, they are very forgiving when pruned. Cut the limbs and shape the tree as you want it. It will put on new sprouts. Prune the new sprouts you don't want. Any sprouts which come from below the current lowest limb, I would automatically remove. They could be a sprout from the rootstock. Fertilize after pruning and you should see new sprouts within 2 or 3 weeks. Pruning may inhibit blooming for the next season but it should bloom the second season.