Hi!
There isn't a way to do this with edges, but if you started with a cube and you havent deleted your history yet, you should be able to reverse the vertex delta values back to normal.
Select the Vertices of your cube, in the channelbox you will see "CVs (click to show)" click on that and then set all the values to 0. This should revert your cube to its original form.
That being said, this method is probably slower than just deleting the object you messed up and creating a new cube.
You can also use the scale tool to get multiple vertices/edges to be in exact the same plane by selecting them and scaling the selection down to 0.
But if you want to work with perfect geometric objects, I would suggest you stick to the primitives and use the history node to implement the main changes you need.
I hope it helps!