Remove domain
If your SaaS domain is also a domain using Cloudflare, you can use your Cloudflare DNS to remove your domain from your SaaS provider.
This means that - if you remove the DNS records pointing to your SaaS provider - Cloudflare will stop routing domain traffic through your SaaS provider and the associated custom hostname will enter a Moved state.
This also means that you need to keep DNS records pointing to your SaaS provider for as long as you are a customer. Otherwise, you could accidentally remove your domain from their services.