How to quickly separate and/or delete extra faces created by extruding? I have made a giant plane and subdivided it with 100 cuts. I am extruding the surfaces to make a "room" if you will.



If the areas are not extruded in the same extrusion, a wall is left between the two extrusions, as you can see at the end of the green arrow. 

What I would like to do is take one of the "squares" on these said walls and delete it. Now I had tried to work around this by grabbing the wall at the top and pulling down on it but the problem with that is it is connected to the walls next to it. So when it moves they move.

Question

Is there a way to delete one specific "square" from a plane or one specific side to a cube? Also, is there a way to 'unhook' or 'unbind' the objects or squares of a plan from one another when scaling or skewing?

Thanks in advance.
By now you are working with "edge" selection mode (2nd button on the header).

Just switch to "faces" mode (the third), select the face you want to delete, press X and choose the preferred option.

Try also the first button (vertex mode).

The fourth on the right lets you also select  vertex, edges or faces hidden by some other geometry.



Another useful function is select some faces, hit P> Selection, then exit edit mode (&#8633; Tab). The selected faces will be no longer be a part of your original object: they are a brand new object.

Additionally if you hit Y instead of P the selection will be separated from the original mesh while remaining part of the same object.