close-up picture:

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Here's what it looked like in Oct of 2011, but I didn't know root girdling back then:

Relax, it's NBD. Your tree will be fine =)

Not a problem in my world. Not sure I'd even really call that a girdling root.

Regardless, someday way in the very distant future, the tree will get old and die. I doubt very much that root will have played any part.

My advice would be not to try hacking/chipping/cutting or somehow trying to remove it. It's a big, established tree. Let it be.

As they say in med school: first do no harm........

It's a little "diverted", but doesn't encircle the trunk. It's in no danger of girdling the trunk.

Average mature sugar maples often look worse than that -- including mine. There is often a "matte" of overlying/underlying roots extending out.

It's no issue.

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Here's a view of the SW side of the trunk of the tree.

Notice the sunscald scar, over 3 feet long.

I lovingly nursed this tree for 8 years after it split open, to keep fungus, bacteria, and insects out of the injury. It is now completely healed.

Good job. Sugar maple wood is durable and it can usually seal over wounds quite well. Red, silver or Norway maples, not so well.