Is there an “undo” button in automations?

Even better than an undo button, you can view your full history of edits for your automation and revert back to virtually any modification you've made. To access your save history, click the “clock” icon on the top-right of the automation and select the version you'd like to revert the automation to. You'll have the option to preview that version of your automation before you make the change.

For more details, check out this help document.