How do you separate selected mesh with vertex keys?

I imported a model from MakeHuman(generates people) that came already rigged and assigned to the mesh. I am trying to duplicate the body, separate it into it’s own mesh so I can make Armor from it to put back onto the body, but I am not able to separate the mesh because it says “Error - you can’t separate with vertex keys” How do I fix this problem?

well as long as I know, if a mesh has shapes ( Vertex keys ) you are not able to separate or joint the mesh with others. Even if you try to modify the mesh adding more vertex, this will destroy your shapes. The only solution is to delete all the shapes even the “Basis”. But be aware that you will loose all your shapes forever and you might not want it. So I would say, can’t be separated.