I was surprised to find that sudo was not installed by default on Debian 8 as it is with Ubuntu. You can debate whether the root account should, or should not be enabled however, I would recommend the use of sudo for audit logging the use of elevated privileges.
Install sudo itself using the command:
apt-get install sudo
Now add your personal account to the sudo group
adduser <username> sudo
You’ll need to either logoff or reload your groups.
Should you chose to disable the root account itself, use the following commands:
sudo passwd -l root usermod --expiredate 1