If you’ve registered a domain at Zyro, you can find it on the Domains page in your Zyro dashboard.
If you don't remember where you've got the 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 always 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 one needs to add or remove specific DNS records (A, CNAME, MX, TXT, etc.), they'd need to do that at Cloudflare, despite the fact that the domain is registered at Hostinger.
However, if one needs to update domain nameservers, they must do that at the platform they've registered the domain. For example, if one has a domain at Hostinger and wants to update the domain nameservers to point the domain to Zyro, they'd need to do that at Hostinger. Once the DNS propagation is over, the domain is completely pointed to Zyro servers, and the domain's DNS zone is also managed from Zyro.