You do not have to do anything to cancel your subscription: it will automatically expire after the end date. To view your current end date, please follow these steps:
Log into MyTunify
Go to "Music”
Click on "Subscriptions”
Look at "End date”
Attention: Do you have automatic renewal on?
Then it's best to turn off auto-renewal by following these steps:
Log into MyTunify
Go to "Music “
Click on "Subscriptions”
Click on the pencil next to the song name
Turn off auto-renewal
Your subscription will automatically end after the end date. After that, you have no obligations.