Active bank and credit card connections in the Banking section can be quickly removed with the following steps:
Disconnecting a Bank Connection
From QuickBooks Online, navigate to the Banking tab. Click the credit card at the top you'd like to remove.
Click the Pencil ✎ icon in the top-right of the account's box and select Edit AccountInfo.
In the bottom-right corner of the Account box, check Disconnect this account on save and click Save and close to remove the banking link.
Check out our thorough guide on removing an active bank connection for additional information. Once you've done this, transactions will no longer be automatically downloaded to this credit card register. If you'd like to fully delete the account, see below:
Deleting an Account Register
Navigate to the Accounting tab and the Chart of Accounts section.
On the drop-down ▼ next to the Credit Card you need to remove, select Delete.
If there is a remaining balance in the account register, you'll be warned that doing this will write off that balance to Opening Balance Equity. Select Yes.
This entire process is demonstrated in the brief video I'm including below:
There's also an informative guide on deleting accounts in QBO for your benefit. With these resources, you'll have that credit card deleted from Banking in no time. Please touch base with me here for all of your future QuickBooks needs. Thanks for coming to the Community, wishing you and your business a successful 2019 ahead.