It is carnosa Krimson Princess (also called rubra). And, yes, it looks to be reverting (some KP clones are quite unstable). Just cut the green growth to make a new plant, if you don't like it.

But if I cut the green leave, will it stay with the white for the rest of the plant ?And the new one will be completely green then ?

If you cut the green growth, it does not guarantee that the plant will not continue to put out solid green growth.

If you decide to make a new pot with all green growth, it is not likely to revert back to variegated growth, but it could happen. Then you just cut thevariegated growth and put it in the pot with Krimson Princess.