Chosen Solution
internal Memory of my Samsung Galaxy S4 runs out. What data can I delete without harm?
Delete without harm? If you are rooted, any of the junk that the carrier put on. Anything Samsung/Android related will need to stay on your phone. Why even do that? Get a Micro SD card for super cheap to add more storage to your phone. It has a micro sd card slot under the rear plastic case and above the battery location. Or, backup all your unneeded music/videos/pictures to your computer and delete them from your phone.
Just transfer every app you possibly can from device storage to external SD. Then make sure all newly added apps are stored to the SD.
