Reduce vertices while keeping geometry same

I just modeled this (not finished):

This is what I want to do for it:

How to do it?

Just manually remove the edgeloops. Select them Using Alt + RMB, Then by pressing X + Edgeloop

you should post a picture of the wire-frame, that would make it easier to tell what would be the best method for reducing the number of vertices

Here’s some wireframe pics:
The side has too many vertices (topright image).

Also, Shift+F makes some faces look ugly. How to make the faces look nicer?