If you bought a domain from Zyro, you can find it on My domains page in your dashboard.
If you can't remember where you bought a domain from, you can use a public domain database WHOIS that can show where is your domain registered and where is it 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 servers. This means that the domain's DNS zone is managed at Cloudflare, too.
In other words, if you needed to add/remove specific DNS records (A, MX, CNAME, etc.), you would need to go to Cloudflare for that, despite the fact the domain is registered at Hostinger.
However, the nameservers themselves are changed at the platform the domain is registered at.
If you want to point the domain elsewhere – to Zyro's servers, for example – you would change the nameservers at Hostinger. Once the DNS propagation is over – your domain is fully pointing to Zyro servers, and the DNS zone is now managed from Zyro, too.