I don’t know how to do it on Cloudflare. I am trying to link a domain to Scalacube, where I am hosting a dedicated server. It wants me to do the following:
Remove these nameservers: rory.ns.cloudflare.com hadlee.ns.cloudflare.com
Replace with ScalaCube’s nameservers: conrad.ns.cloudflare.com dina.ns.cloudflare.com
But there is no way to edit the assigned nameservers for the domain. Is it a record I am supposed to create? Creating an NS record with root to these nameserver gives me a validation error. Not sure what to do.
If Cloudflare is your domain registrar, you can’t do this. There is no reason you should have to; you should be able to add the appropriate DNS record yourself.
However, I looked on their site and all I can find are the same instructions you have. You should contact their support and ask them what DNS entry (or entries) you need to create in order to use their service with DNS hosted elsewhere. Then you can add those records in your Cloudflare dashboard.