mysqladmin is a command to change ROOT password
To setup root password for first time, use mysqladmin command at shell prompt as follows:
# mysqladmin -u root password NEWPASSWORD
if you want to change (or update) a root password, then you need to use following command
# mysqladmin -u root -p’oldpassword’ password newpass
For example, If old password is Redhat, and set new password to Redhat@123, enter:
# mysqladmin -u root -p'Redhat' password 'Redhat@123'