Can a customer change their nameservers. If a customer buys a domain name from me but does not want to host it on my server can they change the nameservers or do I have to?
As long as the person who bought it is listed with the registrar – even if you are a reseller and listed as technical contact – Most registrars allow the Administrative contact (the customer) to make that change on their site. Exactly how it woks will vary from registrar to registrar.
What I meant was if I use whois.cart and sell domain names through my server will they be able to change the nameservers. Is that done in interwox?
A domain’s “authoritative” nameservers are set at the registrar level (where the domain is registered), and this is completely independent of the billing system you use. If you point that domain’s authoritative nameservers to an InterWorx box, you’ll also need to make sure the NS records (in DNS management in NodeWorx) also matches.
If they point the domain’s authoritative nameservers to a non-InterWorx box, they’ll need to check the appropriate DNS settings on that server.