What happens if you long-press on the icon? That will generally bring up a menu that will either allow you to uninstall the app or take you to the app info which is the page you'd see from the "application manager" and allow you to uninstall them there. If the apps were pre-installed on your device you MAY not be able to remove them, you may need to just disable them.
If you tell us what device you have we might be able to give you exact steps.
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Welcome to Android Central! In general, go to your system settings, then Apps -- that's the "application manager." Select Facebook there and see if there's an Uninstall or Disable option.