Joining this thread, LWFORTEM.

There isn't an option to void or cancel a purchase order in QuickBooks Online (QBO). You might consider creating a copy of the purchase order then delete the original one. I can walk you through how to do it:

1. Go to the Expenses menu and choose the Expenses tab.
2. Click the Filter dropdown and select Purchase Order as the Type.
3. Click Apply.
4. Locate the purchase order and click it.
5. Click the More option below and choose Copy.
6. In case you want to make changes to the copy, you can do so.
7. Once done, click Save and close.

Here's an article you can read to learn more about purchase orders: How to Use Purchase Order?

You'll need to do it one at a time to delete the Purchase Order. To do it, open the purchase order, and then click More. Then, select Delete. 

1. Click the Search icon on the top menu.
2. Choose Advanced Search.
3. In the Search drop-down button and select Purchase Orders.
4. Hit Search, then choose on the purchase order to open it.
5. Click More at the bottom page of the purchase order.
6. Choose Delete.
7. Then, click the Yes button to confirm.

On the other hand, you can browse the list of common questions about purchase order in this article: Explore actions within a purchase order

Please let me know if you have further questions or concerns. You can always count on us here in the Community to get you back to business every step of the way. Take care and enjoy the day!