One makes it easy to remove external accounts you had previously linked. This will break the connection between these two accounts and block the ability to transfer funds between them. If needed, you can always link them again.
If interested in removing a linked external account, please follow these steps:
1) Open the One application
4) Click on the Details tab
5) Click on the 'Linked Accounts' option
6) Click on the 'Unlink' link next to the account you would like to remove
Please note that it is currently only available in the latest version of the One Mobile app. If you don’t see the option listed, please click here to update your version of One.