In the Web-based Workflow Designer you can reverse and reapply the steps you have performend to configure a workflow.
The redo/undo panel allows to quickly correct mistakes or revert to previous states.
Click on Undo in the sidebar to see a lists of the steps you performed.
Click on a previous step to revert to that stage. All subsequent steps will be deleted.
With Redo you can reverse the undo action.
See the image below how it is done - click to enlarge:
Use of the undo/redo panel in Web-based Workflow Designer
Note
The steps you performed on the workflow canvas are listed only for the current session. If you close the workflow - by clicking on the X in the tab - the configuration history up to that point will not be available the next time you open the workflow. You can go back to the dashboard without closing the workflow configuration.