how can I root my phone with erasing anything?

[jojos1234]

I just want to be able to access the build number. I did some research and I found out I need to root my phone but I read it can void my warranty etc. how do I root it safely to access my build number and then unroot it?

 

[B. Diddy]

Moved to the S6 Rooting forum.

 

[lucianus_luciferus]

you don't need to root to see the build number.
go to settings, about device, software info, build number