If you dig around it carefully you may find that the entire root-stock (specimen is clearly grafted) is going around like this - such is not unusual, unfortunately. In which case all you can do is remove and replace the tree - in order to prevent having it grow perhaps quite large, only to lean over or topple, maybe suddenly.

Or slowly fill in with soil over a period of years, so that it ends up a little above the graft line. This in the hope that the scion forms its own, new root system above the graft line.

Thanks. I thought that Girdling roots will only occur at the root flare.

Also why do the nurseries allow tree's to be sold with root problems like that? Shouldn't they correct the root problems before they're shipped to local nurseries?

Yes cut those next to the trunk. Wait until the tree goes dormant to do it. If you can't get a pruner in there, use a hammer and a chisel - it works quite well, just do it slowly and carefully and watch your aim. The tree should be fine.

Cutting the upper ones only won't assure the tree will succeed later if all of the roots are in a wad.

Based on the annual growth schedule of the roots of cold climate adapted plants end of winter, before spring bud break would probably be the best time. With fall the poorest.

The common problem is stock being left too long in bands or other small containers, with no correction ever occurring at any stage in production. So all the roots are affected.

And I have observed that there seems to be this idea present that material earmarked for future use as root-stock can be left sitting around even longer in the same small cells than other stock. So that some of the worst finished specimens I see presented to the retail market are grafted ones. Including quite costly grafted ones.

Oy sure the whole thing may be a mess, but cut the bad ones that you can see and then hope for the best. I have done this countless times. If you have the energy to pull the whole thing and clean it out, great. But that produces stress, too (and you sure don't want to do it unless the tree is dormant). I've done it in mid-summer but I wouldn't recommend that. Best time to correct these problems (if you are not the grower) is when you plant the tree.