Yes, you need to wait for the refund before starting the Amend process.
See this TurboTax support FAQ for undoing an amended tax return using the online editions - <a rel="nofollow" target="_blank" href="
https://ttlc.intuit.com/questions/2552802-how-do-i-cancel-or-undo-an-amended-return-in-turbotax-onli...>
