Yes, you may change hostname on your VPS.

To do it, follow those steps:

1. Login to your VPS via SSH client.

2. Open hosts file:

vi /etc/hosts

3. Find the line which contains your hostname:

<server shared ip> <hostname>.<domain>.<extension>

Replace this line with the following line:

<server shared ip> <new hostname>.<domain>.<extension>

4. Save this file and close it.

Notice: additional files must be updated with new hostname.

/etc/sysconfig/network

and

/proc/sys/kernel/hostname

Hostname on VPS should be changed.