Create a non-root user in a brand-new Linode. This assumes that you want to use the same SSH key to login with the new user, and that you want that user to have sudo
power.
ssh root@<linode-ip>
# Add a new user named 'blachniet' by following the prompts
root@localhost:~$ adduser
# Give this user sudo permissions
root@localhost:~$ cat <<EOF > /etc/sudoers.d/blachniet
blachniet ALL=(ALL) ALL
EOF
# Copy SSH authorized_keys
root@localhost:~$ cp -r .ssh /home/blachniet/.ssh/
root@localhost:~$ chown -R blachniet:blachniet /home/blachniet/.ssh/
root@localhost:~$ chmod 700 /home/blachniet/.ssh/
root@localhost:~$ exit
ssh blachniet@<linode-ip>
blachniet@localhost:~$ sudo ls