There's a big difference between disconnecting an account from online banking and deleting one from your chart of accounts. Here are a few tips to keep in mind.
Disconnecting accounts connected to online banking
Instead of deleting accounts that are connected to online banking, we recommend disconnecting it. This simply stops QuickBooks from downloading new transactions. If you disconnect an account from online banking, your existing accounting data won't change. You can reconnect it any time to start downloading transactions again.
When you disconnect, QuickBooks deletes transactions that still need to be categorised in the For review tab. Upon reconnecting, depending on the date you want transactions to be brought into QuickBooks, these might appear again or not.
Deleting accounts
Deleting an account is permanent. You won't see it on menus or lists anymore. While you hold on to your existing data on financial reports, you may delete transaction records. It's very hard to get transactions back into the account if you decide to recreate it later on.
If transactions in a deleted account are tied to other accounts in QuickBooks Online, they will remain in those accounts. For example, if you delete a credit card account, but you made card payments from your current account, the record of those transactions stay in the current account.
Deleting an account from your chart of accounts is permanent. If you're sure this is what you want to do, here's how to delete an account and make it inactive.