In linux, root user is the most privileged user and it has access to all the commands and files. It is also known as the superuser or administrator.
By default, whenever you login in GCP Linux VM using SSH provided by GCP or using the custom SSH, it login as gcp_username user or as ssh_username respectively.
To login as the root user, first set the root password.
To set the root password, use
This command can be used to change current user's password or if the user is member sudo group then it can change the password of root or other users.
passwd [options] [username]
sudoif it gives permission error.
sudo passwd root
Enter the new password and retype the new password.
Login as root user
su command to change the user.