Can anybody tell me if I can remove some of the variations in a listing.

In the pic attached,  I need to remove some of the listings from the first screen of the variation wizard. I know that I cannot remove those which have had sales, but there does not seem to be a way to tidy up and/or remove some of the ones were added in error.

It seems that once you have added in a variation, and moved ahead on the screens, you cannot go back and alter anything, you can only add new ones. Pretty stupid, especially if you mess up on 1cm measurements and just want to alter them.