How to remove the password expiry for DB users in Oracle DB.

DDLs to unlock the db user
ALTER USER sys IDENTIFIED BY new_password account unlock;
ALTER USER dbsnmp IDENTIFIED BY new_password account unlock;
ALTER USER sysman IDENTIFIED BY new_password account unlock;
ALTER USER system IDENTIFIED BY new_password account unlock;

DDL to remove users password expiry.
ALTER PROFILE DEFAULT LIMIT password_life_time UNLIMITED;

Statement to verify the User account status and expiry date.
SELECT username,ACCOUNT_STATUS,EXPIRY_DATE FROM dba_users;