It's not hard to write procedures to do this (to pop a vertex from the stack of vertices and then reduce the indices of all triangles that had references to indices above the and if they had references to the removed vertex, delete the triangle).
I had these procedures in my GL engine at one point (used my stack functions to push/pop the data), so I know that it's not hard to do.
I had these procedures in my GL engine at one point (used my stack functions to push/pop the data), so I know that it's not hard to do.