Is it possible to change the hostname?
Are you talking about PE? Not in cloud page, but maybe with Outsystems.

In a private server what you can edit is Server Name, Server DNS, and Frontends.
I am talking about in following Menu Path:
Administration--> Enviroment Configuration
You want to change the hostname in linux server or centox or any kind? I am not clear from your question?
Here I would like to change your instructions in linux and centox

This is one of the problems often encountered while working with CENTOS - even in LAB environment or actual deployment. The following article guides you please change the name (hostname) of centos quickly. 
  To check the name of the current machine, use the hostname command 
If the command "hostname ten_moi" then restart your computer after the old name will.
The information about the name of the machine located in the following file: / etc / sysconfig / network and / etc / hosts, in a set of guidelines is to change the name server settings CENOTS WINSCP need of repair or reconfiguration of 2 on file. 
Performed on CENTOS 
So below is how to change the name of the server you installed CENTOS quickly and most convenient way users will not need to modify the configuration file by hand anymore.

Also how can this be applied to the general Linux machine, however the command and the path may be different.

How to perform on ubuntu

If necessary, you can change to the file / etc / hosts to complete configuration
Back to the original question (sorry, forgot to return here).

The host name is the url your server will use. If you configured a domain for the server, you should use it there so URLs are correctly built.

Check an explanation here