Hi, I had two jade plants in one pot. Both developed root rot. The big one was beyond saving as the rot had gone all the way to branches. I'm trying to save the small one but not sure how much should I cut. I've attached an image of the cross-section after cutting.

The above photo was taken after I cut part of the root, I noticed there is a dark ring in the centre, so I decided to cut more.

This is the cross-section after another cut, there is still a ring in the middle but not as dark as the ring in the first cut.

Can someone please tell me if this is good enough or I should cut more?

On the left is the small one I'm trying to save. the big one has been chopped into pieces and you can see the big dark ring.