/Accounts/:AccountSid/SIP/Domains/{{SipDomainSid}}{{mediaTypeExtension}}

DELETE {{baseUrl}}/Accounts/:AccountSid/SIP/Domains/{{SipDomainSid}}{{mediaTypeExtension}}

Delete a domain. If you have created subdomains of a domain, you will not be able to delete the domain until you first delete all subdomains of it.