I can't delete bad piggies off Galaxy S4 I installed the game thinking I'd play it, but I changed my mind. Anyway, that's not too important. I clicked uninstall, and it does say it uninstalled it, but in the application manager, it is still taking up 108 MB, though listed as "Not installed." 

If I go to the play store, and try to get the game again, it installs instantly, proving to me that the app is still somewhere on the phone (I don't have 100 MBps internet) How do I get rid of the app completely?

If it's important, I use Android Lollipop 5.0.1.
Do you have root? I don't know, so I will just say both ways, with and without root.

--With root

Get a Root File Explorer (I recommend ES File Explorer), open the menu, scroll down to the root option and turn in on. Then navigate to /data/app and delete the app file. The file name should be the apps package name. That would be com.rovio.BadPiggies.apk. Delete that. I can't remember how Lollipop installs apps, so if /data/app is full of directories, then just delete the directory named com.rovio.BadPiggies.

--Without root

You need a computer for this. Download ADB (I'll give you a link) to your computer. cd to where ADB was downloaded to. Plug your phone into the computer. Open up a terminal (or CMD if your on Windows). Run adb devices. It should list your devices serial number, and it's status. Allow the computer to use ADB. The prompt will be on your phone. 
Run adb shell, then run the following commands in order:

cd /data/app
ls


If ls's output was a bunch of files ending in .apk then run rm com.rovio.BadPiggies.apk, and if it wasn't, then run rm com.rovio.BadPiggies.

Hope this helps