If you forget your password, you can only reset it using the recovery email you add during setup.
However, if you are still logged in and can't access that email, you can request a password reset to remove the password after 7 days – but can be cancelled from any of your devices.
Go to Settings > Privacy and Security > Two-Step Verification to add or change your password.
You can also enable a local Passcode Lock – a PIN code that is required to open the app and view your chats.
