The B&W process uses a bleach before the 2nd Developer to remove the processed silver, converting it to a very soluble silver salt. This doesn't affect the unexposed so undeveloped part of the film, which is chemically fogged and developed with a colour developer.

So even if you did remove the first part of the processed silver you'd still need to bleach the redeveloped secondary image as that contains silver as well as the colour dyes formed during the color development stage.