In Roblox Studio, the usual way to undo is Ctrl+Z on Windows or Command+Z on Mac, and in the newer UI it may also be under the Edit menu as Undo/Redo. If you mean Lemonade AI inside Roblox rather than Studio, the undo option is not clearly documented from the results I found, so the safest approach is to look for the same keyboard shortcut first and then check whether the app has an Edit or history menu.

Fast steps

  1. Try Ctrl+Z or Command+Z immediately after the action.
  2. If that does nothing, open Edit and look for Undo or Redo.
  3. In some Roblox Studio layouts, the buttons may be hidden but still available through the toolbar or menu.

If you are in a game

If “Lemonade AI” is a Roblox game or in-game editor, undo may depend on the creator’s interface rather than Roblox itself, so the controls can be different from Studio. A quick test is to use the shortcut first, because many Roblox tools map undo to the standard shortcut even when the button is not visible.

Most likely answer

For most Roblox editing setups, undo = Ctrl+Z / Command+Z. If you see a top menu, check Edit → Undo.