I can’t seem to delete an app completely

So I have this problem: my iPhone doesn’t delete an app completely. A few days ago, I deleted Twitter. Then yesterday, when I rebooted my phone for other reasons, it showed up on my home screen as a white icon with grey lines and as if I would have four new notifications. I tried to delete it and went to App Store afterwards, and it showed under Twitter that I’d still have it! The ’download’ button was replaced with an ’open’ button. I freaked out and rebooted my phone again. It still showed up! And in the Settings->General->Manage storage it showed up (until it disappeared from there about five minutes ago), as well as the app list in Settings. In the Manage storage section I tried to delete it, but it doesn’t delete. I also can’t offload it. Also, Twitter has an update that I can download, but I don’t even have the app anymore. So I don’t know what it updates then. Can someone please help? I have the iPhone 5s.