First, you need to log in SSH or Putty to your server
then use command passwd to change the password. below example is changed the root password for a Centos:
[root @ VM ~]# passwd (Changing password for user root.)
New password: (You should type your new password here)
Retype new password: (You should retype your new password again)
[root @ VM ~]# all authentication tokens updated successfully. (Your password change successfully)
