Terms:
ICANN: The organization responsible for coordinating the maintenance of the domain name system (among other things).
Registrar: A company authorized to update ICANN database on behalf of registrants. Google, GoDadddy, Enom, etc are registrars
Registrants: An entity that wants to register a domain name. In this case, Zoho is a registrant, but it could also be an individual. This is your role if you 'own' a domain.
Authoritative Name Server: A domain name server that is considered authoritative for a specific domain.
Stuff registrars can do (among other things):
1.) They can update the ICANN database to disable a domain completely[1]
2.) They can replace your authoritative name servers with their own or someone else's (ex: botnet domains being reassigned to a security company for dismantling via court order)[2]
3.) If the authoritative name servers for a domain are owned by the registrar, then the registrar can merely change the DNS entries themselves to point to something other than the domain owner's wishes.
[0] - https://en.wikipedia.org/wiki/ICANN
[1] - https://www.icann.org/resources/pages/epp-status-codes-2014-...
[2] - https://www.icann.org/en/system/files/files/guidance-domain-...