DNS just resolves domains to their corresponding IP address, so if both www.domain.com and domian.co are setup to point to the same IP address then you are all set.

What you are probably referring to is redirecting an HTTP request to www.domain.com to domain.com which would require updating your HTTP server. If you are using nginx, then you would need to update your nginx configuration to do that.

Likewise if you are using a different webserver then it would require you to update the configuration there.

To do it via nginx here is a tutorial:
https://www.digitalocean.com/community/tutorials/how-to-redirect-www-to-non-www-with-nginx-on-centos-7