Do I need an internet law attorney?

This is probably more of a contractual issue than "internet law" per se.

This will be governed principally be state law; I am not licensed to practice in NC so can't provide you with much guidance here other than to look to the contract that you and the designer entered into. The contract and statement of work should explain what the work for hire is, and how payment is to be made.

By all means, consult with an attorney to review the contract with the designer to determine your rights and remedies under that contract.

If your designer can shut down the site, then you're NOT the owner as far as the ISP is concerned, since only the domain name's registrant/owner can do that. Your registrar assumes that whoever is the registrar when the site is set up, is the owner, and they won't help you resolve an internal ownership issues between you and your employee, or you and your partner, who's now acting on their own behalf.

As my colleague noted, this is a contractual issue between you and your designer. Hopeflly you have a written contract that spells out your ownership of the website and its contents and that hires them on a "work for hire" basis so you own their work as well, and also sets out a payment schedule for the work they haven't done yet but are demanding payment for.

You may need to sue for conversion of your site, breach of contract, etc., so consult an IP litigator ASAP to disclose all the facts of your situation and get some specifiic advice.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

You cannot conclude that you own the site. And the critical issue as has been pointed out is your contractually supported rights to the work. One thing that your contract should specify is whether this is a "work for hire" and whether there is a transfer and/or assignment of copyright.

Secondly, since payment as you mentioned is still outstanding that might be a basis for the designer to resist enforcement of the agreement. So you should be prepared to parse the specific facts and context of the dispute. That being said, you may want to have an attorney review the operative agreements and the nature of the dispute.

I hope this helps.

Disclaimer: This answer is for informational purposes only and does not constitute general or specific legal advice, nor create an attorney client relationship.