Note: IF you don´t see the red sign you need to contact the gym/club and ask them for advice.
In app:
Go to your account and click Subscriptions
Find the subscription you want to cancel
There you can click Cancel subscription
Then this pops up and you click Yes
In web:
If you want to cancel a recurring subscription you go to the shop, https://www.sportabler.com/shop/ and click on Registrations.
Find the subscription and click on See more
Then the subscription opens up, there you can click on Cancel subscription
This window will open and then you click on Confirm.