Problem with Phone location

[Lakarnum]

Hello
So basically I used to live in South Korea for 2 full years
I bought my Galaxy S8+ there in official Samsung Store
However problem with buying phones in South Korea is that you need to register them for Korean Phone number
So basically my phone had no carrier when I bought it but it is still registered for "KT-KOREAN TELECOM"
So whenever I reset my phone I get Samsung logo and also KT logo

Well. I went back to my country (Poland) and I can use my phone with Polish carrier without an issue
However, Phone is still kinda "Locked" (?) to korean location.
So when, for example I downloaded Samsung Members app on my phone is is in Korean and I cannot sign up for tests of new Samsung UI One

I am writting to ask you if there is any possible way to fix this issue and register my phone as polish phone? Or just to unregister somehow from KT?

Mostly I want to do it just to get new UI one and also get rid of little bit of blootwware i had installed

Thank you for you help!

 

[Rukbat]

First back up everything you've added since you got the phone - music, pictures, videos, apps - you'll lose it all. Then flash the Polish version of the ROM (see [Samsung] How to flash Stock ROM via ODIN). Then restore what you backed up and everything should be working in Polish.