Downgrade Galaxy S6 from Marshmallow 6.0 to Lollipop 5

[AC Question]

I wanted to downgrade my galaxy s6 from marshmallow 6.0 to lollipop 5, however all of instruction was based on windows platform. Anybody have idea how can I do it on mac?

 

[Rukbat]

You can't "downgrade" Android versions, you have to flash the ROM you want - 5, in this case. See [Samsung] How to flash Stock ROM via ODIN. You'll lose all your downloaded apps, pics, music, data, etc., so back everything up (see Backing up an Android Device).

For Macs, see Download Odin (Jdoin3) For MAC OSX | TechBeasts