If the change was not published you have two options:
1
Click done at the top right, then choose the discard option to undo all changes since the last time the page was published.
2
If you just made the change and the page builder is still active at the top left, click "currently editing...". Then click history, and you will see each change that was made. You can click on a change to undo all changes made after the change you select.
If the change was published (Done then publish option):
1
If the changes were published, activate the page builder, then click “currently editing…” at the top left. Click revisions and choose a revision that has the content you want. Once you choose one you'll see it, then you can accept it or choose a different revision until you find the one you want.
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