How to uninstall a third party firmware on Galaxy S5 and update to the official one?

[AC Question]

I have a Galaxy S5 with Android 4.4.2 which I downloaded from Sammobile. Before this version, I had Android 5.0 as the official Samsung update. My question is, how do I uninstall the firmware and have the 5.0 again? Is it possible to do so without downloading anything from a third party? I've tried uploading but it says the newest updates are already installed.

 

[Rukbat]

Wait 24 hours, then try again. (You can't download more than once in 24 hours - if you try, you get told that you're up to date.)

The firmware at Sammobile is the official Samsung firmware, so if 5.0 is up there, download it, boot into Download mode and install it. (Same rules - you'll lose everything.) If you "uninstall" an OS, you're left with a phone that only has Download mode (if you're lucky). You install a different version, wiping out the version in the phone.

If it's not there, see the proper S5 forum (the one for your carrier) at XDA Forums to see if anyone posted the stock 5.0 ROM.