Alter existing user options.
ALTER USER user_name WITH PASSWORD 'password' NOSUPERUSER | SUPERUSER
In the synopsis section of each statement, formatting has the following meaning:
A semicolon that terminates cqlsh statements is not included in the synopsis.
Superusers can change a user's password or superuser status. To prevent disabling all superusers, superusers cannot change their own superuser status. Ordinary users can change only their own password.
Enclose the user name in single quotation marks if it contains non-alphanumeric characters. Enclose the password in single quotation marks.
ALTER USER moss WITH PASSWORD 'bestReceiver';