Скачать или смотреть How to change Root Username & Password

Avoid use the 'root' username for your database over reasons of security.
Here, we'll alter the 'root' username's password and give it a new name.
In MySQL 8.0+, you can change the root password in the following way:

Change 'new_password' to the root password you choose.
ALTER USER 'root'@'localhost' IDENTIFIED BY 'new_password';

Exists a user: Make sure the'mysql' database contains the 'root' user. The user's password cannot be updated if it does not exist. Use the following SQL query to see if the 'root' user is present:

SELECT User FROM mysql.user WHERE User = 'root';

In MySQL , changing the root username can be a difficult and even dangerous procedure. It involves creating a new user with the desired username, giving them root permissions, and then deactivating or deleting the previous root user.

Use the current root user to log in:

Log into MySQL as the logged-in root user and launch a terminal or command prompt:
mysql -u source_user -p

Establish a New User:
Specify the appropriate username and a strong password when creating a new user. Change 'new_username' and 'new_password' to the values you prefer:

CREATE USER 'new_username'@'localhost' IDENTIFIED BY 'new_password';

Grant the New User Privileges:
Give the newly created user the same rights as the active root user.

GRANT ALL PRIVILEGES ON . TO 'root'@'localhost' WITH GRANT OPTION;

Flush Rights:
FLUSH PRIVILEGES;

After giving the new user privileges, flush the privileges to make the changes take effect:
Remove or disable the previous root user:

It's a good idea to disable or delete the old root user for security reasons. SQL commands like these can be used to do this:
ALTER USER 'root'@'localhost' ACCOUNT LOCK;

To remove the previous root user:
Make sure you have successfully transferred all privileges to the new account before removing the old root user.

DROP USER 'root'@'localhost';

If you don't do it right, deleting the old root user could potentially lock you out of the database.Throughout this procedure, make sure you have backups and follow according to standard practices for database security.