How to uninstall an app on the Iphone? The holding it down doesn't work on my phone?

When I hold down the app I want to delete the X never appears it just wiggles. Help!

Added (1). I want to delete apps that I have installed.

Settings>General>usage> app>delete

The core apps that the phone comes with(Clock, Settings, Weather, Photos, Email, Phone, Messages, App Store, Stocks, Maps… Etc) are required by the iOS and can't be deleted.

What app is it? If it's an application that came with your phone, then you can't delete it. Some examples include Clock, Safari, Maps, and Game Center. You'll have to put in a folder or try to put it out of the way if you don't like it. If it's an application you downloaded, then you can probably try a hard reset and try again, or you can wipe your phone to delete it. However, if you wipe your phone, then you'll lose all your other data too. However, this app just sounds like an app built-in by Apple. You can't delete those, at least not without manipulating your phone in some other way such as jailbreaking. Since I've never jailbroken my iPhone, though, I wouldn't know there was a tweak for that. I wouldn't be surprised if there was one, however.