1. INSTALL A CUSTOM ROM
It’s time to ditch that stock Samsung ROM. You’ll want to download XtreStoLite Deo-Mod Edition 2.4 and its Aroma Add-On Package from the Galaxy S6 XDA forums. This is essentially based on Samsung’s stock files (which means it should be very stable), but with all the custom software stripped out.
Put both .zip files on your phone and then boot into recovery mode (Power + Home + Volume Up buttons). Next, hit 'Wipe' in the tiled menu and work the slider to factory reset your phone. After that, tap 'Advanced Wipe' and check the Dalvik Cache, Cache, and System options, and swipe to wipe those components.
Now you’re all set to flash the ROM. Return to the main menu and hit 'Install'. Navigate to the folder where you placed the ROM, select the right file, and then swipe to flash.
This time, pay closer attention to the installation menu. You’ll be prompted to select one of two custom kernels. Select 'Vindicator', and continue on with the installation. When that’s finished, you can reboot the device.