The business's real bank accounts.
Adding a bank account creates a ledger account
When you add a bank account, the system creates a matching ledger account under assets and takes its code from the banking band automatically.
So you do not need to go to the chart of accounts and make one — and you should not, or you will end up with two accounts for one bank.
Gateway money does not go straight to the bank
A sale paid through a payment gateway lands first in a clearing account, not in your bank account. That money has not reached you yet.
When the gateway actually pays out, you record a settlement: the net amount goes to the bank, the gateway's fee becomes an expense, and the clearing account empties.
If the clearing account keeps growing, settlements are not being recorded.
Deactivate rather than delete
A bank account with entries against it is part of the books' history. For a bank you no longer use, deactivating is the right move: it drops out of the pickers and its history stays.