In most cases your customers will cancel & manage their subscription through their account. In the scenario you're asked or need to edit & or cancel a customers subscription, this can be done through your Site Admin > Subscriptions
In the scenario you need to cancel a customers subscription, this can be done in a couple ways; through the Mavenseed web interface, or directly from Stripe.
To reach the members subscription, click on Subscriptions in your Site Admin menu. Under the ALL SUBSCRIPTIONS tab, search for the member. Once you see them click View.
In the upper right hand corner, click the three vertical dot menu to bring up the Cancel option. Clicking the Cancel menu will confirm your request one more time before processing. This will cancel the customers subscription to cancel at period end on Mavenseed and Stripe.
If you need to completely remove all records of the subscription being attached to your customer. This is when you'd Delete Subscription. Keep in mind this does not update Stripe, and it's recommended that you also remove the Subscription from the Customers Stripe account.