Removing Extra Geometry?

I’m wondering, say for example, I make two cubes, side by side, and select both and ctrl+J to make them one single object. Now how could I remove the vertices in the middle to make a simple rectangle with this? In simple, how can I simplify the geometry of an object WITHOUT losing the faces?

I understand I could just make a rectangle, but this is the simplest way I can explain what I am looking for. Basically a reverse knife tool :wink:

ve also tried selecting the four rectange corners and hitting f to make it a face, but beyond that, there are still the vertices in the middle.

press x, and, at the bottom, is a option: edge loop.

press it when the edges you want gone are selected.

To be slightly more precise,

You will want to have the cubes so that edge you want to eliminate is lined up. Then remove doubles. Switching to wireframe view delete the face that is left in the center of the object. Then you will be able to do x->edge loop.

Removing the edge loop worked, thanks a ton!