Show all users:
SELECT user, host FROM mysql.user;
Create user:
create user '<user>'@'<host>' identified by '<password>';
Add permissions to the user:
grant all privileges on '<db-name>'.* to '<user>'@'<host>';
Delete user, drop user or user remove:
DROP USER '<user>'@'<host>';
Change user password:
ALTER USER '<user>'@'<host>' IDENTIFIED BY '<new-password>';
FLUSH PRIVILEGES;
All this applies for mysql version:
5.7.27