How to change the hostname on a dedicated server?

Question

CentOS

The address of my site, hereinafter - site.com
The address of the dedicated server provider, hereinafter - provider.com.
I ordered a dedicated server, and 2 IP addresses (to create my own ns-servers).
Server: CentOS 6, Apache + nginx.
The site site.com is located on the server (the domain registrar has DNS - ns1.site.com and ns2.site.com) The
provider has issued a link to access the ISPmanager panel -
dsnl77.provider.com 2ip.ru/whois ), then a link to the ISPmanager panel is displayed as the host name, and the provider of the dedicated server is also determined.
Question: How can I change the hostname (let's say host.site.com)?
I need to hide server provider information.

Answer 1

Question: How can I change the hostname (let's say host.site.com)?

If I understood you correctly, then ask the provider to register the PTR records you need for the IP addresses you rent.

I need to hide server provider information

I won't even ask why. If you rent an ISP's IP addresses, anyone can find out information about your ISP. If you have your own PI network (prefix of the IPv4 address space), then anyone can find out information about your provider. The very idea of ​​granting access to certain resources and at the same time "hide" their characteristics is rather controversial.