How to extrude inwards without leaving faces? Here is the image to explain what i want



left box shows how i have set loopcuts (green is the face that i am extruding and moving). Middle one is what i want to get. The right is the issue with blender. the red faces will remain. (i have removed doubles on those faces) So is it possible to extrude inwards so that you dont have those faces hanging ? I know i could just delete those faces and thats it. but if you have lot of elements with similar idea it will get time consuming.  Thanks
Follow these steps

1) Go on Face select 



2) Select the faces you want to "block" and click on Offset Edge slide



In this way these 2 faces will be indipendent from the others

3) Move your middle face in the position you prefer. Remember: move it, not extrude.



4) Select all your mesh and press w --> Remove doubles