While we'd be genuinely sorry to see you go, if you're set on unlinking your Sarwa Classic account from Sarwa, you must contact Interactive Brokers directly to make the request.
You can get in touch with them directly from the IBKR dashboard or by contacting their customer support line. The contact number is the following: UK +44 20 374 47300
For email inquiries and additional contact details, please refer to IBKR's support resource page accessible here.