If you’ve bought a domain from Zyro, you can find it on the My domains page in your dashboard.
If you don't remember where you've got a domain from, you can use the public domain database WHOIS. It will show you where your domain is registered and where it is pointing to via nameservers.
The nameservers also indicate where the domain's DNS zone is managed from. In the example above, the domain is registered at Hostinger but pointed to Cloudflare's servers. It means that the domain's DNS zone is also managed from Cloudflare.
Therefore, if you needed to add or remove specific DNS records (A, CNAME, MX, TXT, etc.), you would need to go to Cloudflare for that, despite the fact that the domain is registered at Hostinger.
However, the nameservers themselves are changed at the platform the domain is registered at. So, to point the domain elsewhere, e.g., Zyro, you would need to update the domain's nameservers at Hostinger. Once the DNS propagation finishes, the domain fully points to Zyro servers; the DNS zone is also managed from Zyro.