If you have the "start at system startup" option checked then isn't it doing what you asked for?
Perhaps unchecking the "start at system startup" checkbox will mean that it doesn't start at system startup. At least worth a try.
This option enable indiwebmanagerapp.service in systemd.
You can check it's status with: systemctl status indiwebmanagerapp.service
Maybe you have another startup script you create in the past for a standalone version of indiwebmanager?
Look in /etc/init.d for something related to indiwebmanager and also using the command systemctl list-unit-files