1. Log in to your Name.com account, click My Account and click my domains on the top left.
2. Click the domain name you would like to manage.
3. Click Name Servers on the left side.
4. Click the Delete All button to clear the current name servers away. Alternatively you can also Delete them 1-by-1 by clicking Delete, on the right hand side.
5. Enter the new nameserver in the empty box labeled Add Name Server and then click the blue Add button. Be sure to only add one at a time. These are the nameservers that need to be added (add all 4):
6. Click Apply Changes
To finish the process, follow the steps here to tell Heroic about your custom domain.