It might happen that the bank account has been closed and you don't use it anymore. So you don't see the account all the time in the left and main Accounts sections (as in the screenshot below), you can hide it (and delete it from view).
1) Select an account and click Edit
2) Select Account closed and hit Save
Now, the account has moved to the very bottom of the screen under the Closed Accounts section, and has disappeared in the left section. If you need to access it, click on the Closed Accounts section and double-click on the desired account.