How do i cancel an invoice but keep their deposit for future

Thanks for posting your question here in the Community forum, @mercedesarenado.

If you don't want the invoice to show on your books, you can delete or void it and have the payment transaction to remain. 

Doing so will have a deposit balance on your customer's account that they can apply in the future. 

To void or delete an invoice, here's what you'll need to do:

1. In the left menu, click Sales. 
2. Go to the Customers tab.
3. Locate and open the customer profile. 
4. Open the Invoice. 
5. Click the More button at the bottom. 
6. Select Void or Delete. 

To learn more about this process, you can read this article: Void or delete transactions in QuickBooks Online.

As always, you can get back to me if you have any additional questions. I'm here for you. Have a great day!