1. Navigate to https://secure.myob.com/
2. Click on Authorisation
3. Under the Authorisation heading, you will have a list of apps that you have authorized in MYOB. Click the Revoke Access button beside the app name, Strongbox (US/AU/EU Edition)
PLEASE NOTE: You may only have Strongbox (US Edition), Strongbox (AU Edition), or Strongbox (EU Edition) so you will typically only have to revoke access to the Strongbox connection specific to your region.