The admin account is unable to perform the same actions as the root account after providing the admin account "Full modify permissions on the CLI via SSH" at "Users and Groups" settings.
The Admin account has full modification rights via the web interface and the full modify permissions on the CLI via SSH but not root access.
It is working as expected that you are unable to “sudo su” because the user do not have root access to execute '/bin/' as root.
Note: “sudo su” will put you into a root environment but it will ask you for your user password instead of the root password.
All the commands are available at
Note: With non-root-level access, some commands permit you to prepend sudo to the command, (X in the sudo column). Some commands (* in the sudo column) provide only partial functionality without sudo.