Why am I unable to remove addons using `addons:detach` from my application ?

Issue

When using heroku addons:detach command, for example: heroku addons:detach HEROKU_POSTGRESQL_BRONZE --app sushi

It is failing with the below error:

HEROKU_POSTGRESQL_BRONZE --app sushi
Detaching HEROKU_POSTGRESQL_BRONZE to postgresql-contoured-xxxxx from ⬢ sushi... !
▸ Cannot destroy last attachment to billing app for resource postgresql-contoured-xxxx

Resolution

• You can only use the addons:detach command for addons which have been attached to an app with heroku addons:attach.

• heroku addons:attach is only used for attaching add-ons which have already been provisioned to another app. i.e they are still billed against the original app and are available to be used by both apps.

• If you want to delete this addon/database you should use heroku addons:destroy.

• You can read more about this here: Attaching an add-on to another app