1.Stop mysql service
2.then run this command

mysqld_safe --skip-grant-tables &

3.mysql -u root
4.Run Below Command:-

 	use mysql;
 	update user set password=PASSWORD("mynewpassword") where User='root';
 	flush privileges;
 	quit

5.stop start mysql service  and you’re good to go 🙂

Reference Link : https://www.howtoforge.com/setting-changing-resetting-mysql-root-passwords