It is not recommended to only have a root user on your server, thus we will setup a new user account.
The process is fairly straight-forward:
adduser username
Provide a secure password and your new user account is created.
We will want occasional higher privileges:
usermod -aG sudo username
And you are done! For increased security, read the "securing your instance" guide to secure your instance.
If you are not able to login with a password after adding a user, you need to change your SSH configuration;
nano /etc/ssh/sshd_config
Search for: "PasswordAuthentication" and set to yes. Save the file and reset SSH.