Self-serve reset is not yet wired. Until it is, the desk rotates passwords by hand on request.
Email support@tradingalpha.net from the address tied to your account. Include your AlphaDesk username and a short statement that you are requesting a reset.
The desk verifies ownership out-of-band (usually via a prior message thread or a video call) and then issues a one-time password you use to sign in, after which the app prompts you to set a new one.
Typical turnaround is within the same trading session. If the request is urgent, mention your timezone.