Extrude Manifold making extra vertices I want to extrude this face using Extrude Manifold tool

but when i do that , its leave the vertices that on the bottom face ;

so is there any thing to do to dissolve the vertices directly without any further to do?
An easy way to get rid of a random vertex in the middle of an edge.
Select the offending vert and double tap G to do a vertex slide.  Move it all the way over to where it is in the same position as one of the vertices on the end.  Enable x-ray view and box select both of the vertices and do a Mesh -&gt; Merge -&gt; By Distance.
Extrude Manifold doesn't automatically generate good topology, unfortunately.  You have several faces here with more than 4 verts even getting rid of those two extra vertices.