What is the first step you should take to fix an alert in secret scanning?

The first step when you receive a secret scanning alert is to revoke the secret if it is still valid. This ensures the secret can no longer be used maliciously. Only after revoking it should you proceed to remove it from the code history and apply other mitigation steps.

Simply deleting the secret from the code does not remove the risk if it hasn’t been revoked — especially since it may already be exposed in commit history.