Can I undo/redo within Uizard?

Yes, you can. Standard undo/redo shortcuts work within Uizard.

Undo - 'Cmd' or 'Ctrl' + 'Z'

Redo - 'Cmd' or 'Ctrl' + 'Y'

Alternatively, you can also click on the 'undo' and 'redo' icons on the lower left-hand side.