Welcome to the Community. I can share some information about the accounts linked to QuickBooks.
If you're referring to a credit card account connected to online banking, yes, you can disconnect it. Please note that it'll remain active in the system but will stop downloading new transactions moving forward.
On the left navigation bar, click the Banking or Transactions menu.
Select the blue tile for your bank account.
Select the pencil ✎ icon to edit the account, then select Edit account info.
Select the Disconnect this account on save checkbox.