How do you DELETE the icons, not replace.
Use the up/down/left/right arrows on the remote to select the icon, then press the menu key on the remote. Select "Uninstall" on the menu and press the OK button on the remote and the app will be removed from the box and the icon will disappear.
If the "Uninstall" option is not available then HiMedia do not want you to remove that app! Some may be system apps which must remain while others like Facebook can be removed but will magically reappear when you reboot your box

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Another way to remove apps is by Settings > More > Apps
and uninstall or disable apps like Facebook, Skype, Moviebar, Clock, Calendar, ... there (but do so at your own risk!)
The "ultimate" solution is to use Titanium Backup and "freeze" out persistent unwanted apps (but that's not so easy!)