Can I change a subdomain to a full domain?
Is it possible to change a subdomain over to be it's own full, stand alone domain?
Yes and no. You can't convert a subdomain into a full domain but you can use a new domain in the same way that you're currently using a subdomain. First, register the domain at your choice of domain registrar.
Then, if you're using the Linode DNS manager, add a new domain zone. We have a guide on the DNS manager here:
From there, make sure to update any virtual host configurations to change the current subdomain to the new domain. We have a guide on virtual hosts in both Apache and Nginx: