Delete anchor pen tool has been replaced with delete vertex and I don't know how to revert it back

It's the same thing. If you use the pen tool (g) and you carefully observe the cursor while using the pen tool, and you combine the Alt/Option or Ctrl/Cmnd modifier keys you can select one or more points, add a point, adjust a bezier handle, control the tension on a RotoBezier path, add points, delete points, break bezier handles, and work through the feather tool without ever going to the menu again. A little practice will make you an expert. 

If a path (mask or shape) is selected in the timeline you can also efficiently use the selection tool (v) to edit your path if you pay attention to the cursor. I do all my initial drawing with the pen tool and about 90% of my editing and animating with the selection tool because it is by far the most efficient way to work on a path.

Do you mean "Delete anchor point tool"? It's not replaced: the tool's name in Photoshop "Delete Anchor Point Tool" and in After effects "Delete Vertex Tool", different names but same functionality