Changing the server timezone is a fairly simple process and can be done with as little as one command via SSH.
If you have cPanel installed on your server, please follow this guide.
If you do not have cPanel, please carry on reading.
Firstly, login to your server as root and enter the following command: ln -f -s /usr/share/zoneinfo/TIMEZONE /etc/localtime
Replace TIMEZONE with your desired timezone (i.e. GMT, EST, etc).
To verify that the change has taken affect, you can run the date command which will look something like this:
Sun July 26 15:48:58 EST 2015