How do I delete an account?

Control-click the account in the sidebar and choose "Delete" from the contextual menu. Banktivity will ask you to confirm that you want to permanently delete the account. All transactions contained within the account will also be deleted. Any transfers in the account will be deleted, but the transactions in other accounts to which those transfers are connected will not be deleted (they simply will no longer show the account in their category fields).

Deleting a loan account will cause any scheduled payments associated with the account to be deleted as well. Deleting an account that is used for online bill pay will also delete any payments associated with the account and listed under "Payments" in the sidebar. Note that these payments will not be canceled, just removed from Banktivity.