Discard every pending Canvas change (the auto-saves of the editor and of the API steps) through the authoring API, which is what "Discard changes" in the Review widget does for one item. Use it to leave the site as it was after a scenario that changed a page without publishing.
Examples
When I discard the pending Canvas changes
And I discard the pending Canvas changes
When we discard the pending Canvas changes
And we discard the Canvas changes
Then I discard the Canvas changes
Pattern
When(/^(I |we )*discard the (?:pending )?Canvas changes$/, …)
Part of @webship-js/drupal-cms-steps (github.com/webship/drupal-cms-steps), a step pack for Webship-js 2.0.x.