To get past this, create a burner email (gmail or duckduckgo or mozilla or hey or icloud) that looks at least a little bit human, send a very angry sounding email to privacy@intelius.com and cc privacy@peopleconnect.us (the company that owns intelius, zabasearch, uspeoplesearch... and a few other spam sites).
Tell them you tried to use their form and it's broken and not showing correct info. You may need to verify your bday or past addresses in an email exchange, but once you do this with 2 or 3 emails, they'll suppress your info from public search. DO NOT send them government ID, even if they ask for it, insist you've already provided enough verification.
Include if you're a Californian / Colorado / EU / Iowa / Utah / Connecticut resident, or if you've had any harassment / stalking issues in the past. (this context provides you with legal leverage if they don't comply with your request - so including it helps you get a faster response)
If they give you anymore trouble beyond that, reach out to our team hello [at] kanary.com. We'll help you escalate the issue.