May have deleted by accident the sonar ring notification sound

When i was using the ring app the other day withmy 3 cameras i was looking at the differrent ring sound notifications available even though i use the 'sonar' sound for all 3 cameras. What i didnt realise when looking through the different sounds was the little red minus icon against each sound notification. Somehow i appear to have removed the sonar sound option which is really annoying asni am having to use other sounds which are not my preference and i cant get the sonar sound back. I have tried deleting cache and data on the app and re-installing bit its still not there. I use a samsumg galaxy note 9 and am really hoping someone can assist me in getting this notification tone back (sonar). Regards Stuart