You can cancel a Direct Debit from your online money account and via the Suits Me mobile app.
After logging in you need to select the Direct Debit page and select which direct debit you want to cancel from there.
You must let the organisation know that you no longer need their subscription or service and that you've cancelled the Direct Debit. If you don't, they may still expect your usual payment.
What is the difference between a standing order and a direct debit?