Can I disable WHM access for the root user?
It is not possible to disable WHM access to the root user. However, you can restrict IP addresses from accessing the service or even allow only specific IP addresses to access WHM via Host Access Control. More on this can be found here:
For additional security, you can also enable Two Factor Authentication so that any attempted logins would also be required to pass Two Factor Authentication before further accessing WHM.
More on this can be found here: