Reply To: Bevel Edges Back to Straight Edges

There are several ways to remove do this,

Edge slide as Omar said is one, but also snapping helps. If you have an object like a cube, you can use vertex snapping to line up the vertices to restore the correct shape, obviously wont work always.

Top Tip: Save often, Save Incrementally.

Did you know you can increase the number of undo steps?

The default is 32, the max is 256.