Yes you can, however only if you're already able to log in.
We are not able to reset your password.
We never store your password on our servers, so we have no way to reset your password. Luckily, this means nobody else has this ability, either.
Changing your password is done on Desktop and Android by logging in and going to Wickr Settings -> Account -> Change Password.
To change the password on iOS, you can tap on your username or avatar in Wickr Settings
Follow the prompts for your device once there: