How to change nameservers to domain

My website hoster uses nameservers so my domain can connect, but cloudflare uses it’s own and so I can’t use both at the same time can I change what cloudflare’s nameservers?

No. Cloudflare’s nameservers need to be primary, they forward requests to your web server(s).

You can subscribe Business plan or convert to contract based Enterprise plan to have a CNAME setup if you don’t want Cloudflare as your authoritative server.

Understanding CNAME setup