You can cancel a Direct Debit Mandate in the Tide app:
Tap: ‘Send’ > ‘Recurring payments’ > ‘Direct Debits’ > select a payment > ‘Cancel Direct Debit’.
If the payee continues to collect Direct Debit payments after you’ve cancelled the mandate, you’ll be entitled to ask for a refund within 24 hours of the Direct Debit collection. To do this, tap ‘Support’ in the app, and we’ll help you. In such cases, make sure to cancel the Direct Debit Mandate through the Tide app right away.
You need to request the cancellation at least 24 hours before the payment due date, and tell the payee about the change.