Greetings, hello267. You can uncheck the credit card and bank/transfer ACH payment options to stop your customer from paying the invoices through QuickBooks. To find these settings, navigate to the Gear icon > Account and settings > click the Sales tab > and then locate them under Invoice payments. Once done, click Save and Done.
Please note that this change only affects future invoices. Payment links on previously sent invoices will remain active.
If you want to stop the payment link for a specific client or just for a single transaction, adjust the settings while you're drafting the invoice. Look for the Payment Methods section on the right side of your screen on the invoice page. From there, you can easily toggle off the switches for Credit Card and Bank Transfer.
Feel free to reply below if you have follow-up questions.