I just want to uninstall Facebook and other apps I don't need or want, but the setting menu won't allow it
Grindale is correct, but there is also an option to disable these apps and it can be done without the need for root access to your phone.
Try going to Settings > Apps and then look for the app that you wish to disable (i.e. Facebook). When you see it, tap on it in order to access the available options. One of these options is "Disable" and it should be right next to "Force stop" and below "Uninstall updates". Just tap on the Disable button and you'll be good.
Hopefully that answered your question!
I think you are referring mostly to the apps that are pre-installed on your phone. You need to have your phone rooted first before you can do this.