If you can still sign in with a passkey, an authenticator app, Google, your phone or your organization’s single sign-on, change it yourself: Settings › Account › Email. With Google, phone or single sign-on, sign in again first; you then have 10 minutes.
If you can’t sign in at all, write to support@kemble.io from the new address with your username and how you used Kemble (the workspaces or communities you’re in). We’ll check it’s you, then send a link to the new address. Your old address is told at once, and nothing changes until the link is opened. Your two-step sign-in and passkeys stay as they are, and every device is signed out.