To remove a vertex from a photometric area, solid, or mask, go to
Ribbon: DM Electrical->Point-by-Point Photometrics-> 
Remove Photometric Vertex
Pulldown Menu: DM Electrical->Point-by-Point Photometrics->Remove Photometric Vertex
You will be prompted to identify the vertex to be removed.
Select point to remove on photometric area, solid, or mask:
The vertex will be removed.