How do I undo?

If you want to undo the last action in your report - be it deleting a chart, changing its location or return to the previous edit of your chart's data table - you can do that by using the buttons above the editor:

Also, while editing a chart's data table, hitting Ctrl+Z will undo last edits but only until you exit the editor.

If you started your project by clicking the single Chart/Map buttons from your Library (as opposed to choosing from templates), after you delete a chart, map, text field or any other object from your report, a message will appear in its place allowing you to Undo the last action: