how to reset password for MySQL 8.0

$ cat /etc/my.cnf.d/passw_policy.cnf
## SHOW VARIABLES LIKE 'validate_password%';

[mysqld]

## password validation
#validate_password.check_user_name=ON
validate_password.length=0
validate_password.mixed_case_count=0
validate_password.number_count=0
validate_password.policy=0
validate_password.special_char_count=0

# disable password lifetime
default_password_lifetime=0


$ systemctl set-environment MYSQLD_OPTS="--skip-grant-tables"

$ service mysqld restart

$ mysql -uroot


SET GLOBAL validate_password.policy=LOW;
ALTER USER USER() IDENTIFIED BY 'new_mysql_root_password';
FLUSH PRIVILEGES;

$ systemctl unset MYSQLD_OPTS="--skip-grant-tables"