A subscription can be cancelled manually. Twikey also cancels all subscriptions of an agreement automatically when that agreement is cancelled, or when a recurring credit card agreement expires because the card has reached its expiry date.
Cancelling is permanent: a cancelled subscription cannot be reactivated. Cancelled subscriptions are stopped, transactions already created can still be sent to the bank and a new subscription can be created from the cancelled one using the start over function.
Click on the subscription to open the details. Here you have a cancel button.

To quickly launch a new subscription based on a cancelled subscription you can click on it and use the Start over option. You then have the option to change any details of the subscription if needed or keep the current ones.
Click on Add to finish and a new subscription is created.
The new subscription:

Transactions already created by the subscription can still be sent to the bank, edited or removed like any other open transactions. Future executions, if there are any, are disregarded since the subscription is stopped.