2 answers ·
asked March 19, 2018 4:35pm
· Lesson: The Subdivide Tool · Course: Mesh Modeling Fundamentals
Whilst in edit mode simply hit Ctrl + Z to undo your previous action (undo works in object mode as well but for things that you do in edit mode you'll want to undo there). Alternatively, hit "Object" in the bottom left of the 3D Viewport and select Undo.
Another thing you can do, if you've missed the Undo window, is try the Un-Subdivide command. This command can be found Edge Specials menu (CTRL+E) and allows you to reduce the density of a consistent mesh. It's a bit finicky but in the right situation can be quite helpful.