DNS Issue, Unable to add custom domain to GitHub Pages

[rexronyjacob]

What is the name of the domain?

www.rexronyjacob.com

What is the error number?

81054

What is the error message?

A CNAME record with that host already exists.

What is the issue you’re encountering

Unable to add custom domain to GitHub

What steps have you taken to resolve the issue?

I am trying to add a custom domain which I bought from cloudflare to my GitHub page, but I am not able to add it based on the steps mentioned in the GitHub notification. When I try to add the dns for GitHub custom domain, the name should be @, it shows an error A CNAME record with that host already exists.
I am also unable to delete

What feature, service or problem is this related to?

DNS records

Screenshot of the error

[sjr]

A CNAME does exist for @ (your domain) already, the one pointing to default-page.cloudflareregistrar.com. If it won’t delete, go here and I believe there should be an option to turn off the parking page…
https://dash.cloudflare.com/?to=/:account/domains