As documented here, setting a dokku superuser actually results in preventing apps from being deleted via the command line, which is a side-effect that likely comes quite unexpected to most users.
Despite the helpful warning message
It appears that you're running this command from the command line. The "dokku-acl" plugin disables this by default for safety. Please check the "dokku-acl" documentation for how to enable command line usage.
it took me some time to figure out what was going on.
Once the relevant feature has been deprecated for long enough, I suggest to move to DOKKU_ACL_ALLOW_COMMAND_LINE=1 as the default.
As documented here, setting a dokku superuser actually results in preventing apps from being deleted via the command line, which is a side-effect that likely comes quite unexpected to most users.
Despite the helpful warning message
it took me some time to figure out what was going on.
Once the relevant feature has been deprecated for long enough, I suggest to move to
DOKKU_ACL_ALLOW_COMMAND_LINE=1
as the default.