If you dig & happen to be digging & see any root get as much as you can, but you could dig down to Australia & still not get it all so don’t go mad. Otherwise let it grow until it is 7-10 cams tall & then gently pull it out, or use a trowel to ease it out, this method supposedly lets it put a lot of its energy into growth & then you pull it out which supposedly weakens it before it can photosynthesise. This method has worked best for me, my 2nd has plot was covered in it. It doesn’t cause a problem to your plants as the roots go too deep to compete for moisture, plus some people say it brings up nutrients. Don’t compost the roots.
Do a search on here, John has an article about it
Also It apparently has lots of uses according to Steph Hafferty who gardens no dig with Charles Dowding.