Signed proposal but don't need everything done we thought

[Jennifer Cropper]

So I accepted and signed a proposal from a contractor to lay plywood, new baseboards and install floating floors with provision that we would demo the existing floor which was slate and pergo.

Where the slate was plywood will need to be laid along with new baseboards just as it is written in the proposal; however, where the pergo was, the new floating floor can go right over the plywood already there and we can just paint the baseboards already there. We did not realize this was the case until we demoed the pergo. 

I am not sure how to handle this change with the contractor as the proposal was already agreed upon and signed which included redoing baseboards and laying plywood in rooms where we realize now that does not need to be done. 

btw this us part of a large job that includes other repairs and remodeling. Please help me out.

Thanks