the growth should fall off on its own, but it looks as if you've got the tubers on a plastic bag - they dry out better left sitting on newspaper or dry sand, sawdust, anything that's dry, and exposed to the air.

You can keep and store the tubers you broke if you like (though I'd bin any really tiny bits) but check them next spring - each bit needs to have an 'eye' to be able to produce growth, so if any of the broken bits don't have eyes, you can dispose of them. Its often hard to tell if there are growth eyes now, but easier in spring.

I'd also have them under a porch or patio roof, and off the ground, in the shade, away from rain or dew, and away from the moisture of the ground.

Thanks they were in a bin and since it was a nice day I lay them on a tarpaulin to brush of the damp soil I have some cardboard boxes and some compost (which I was going to dry out )to put them in

But if you spread them out on old newspaper in the shed or somewhere, out of the wet, open to the air,the soil dries and crumbles off anyway. Then store them in your dry compost in boxes.