Lumia 820 - How can I rollback to 8.1 from Preview 10136?

[Windows Central Question]

Recovery tool says I have the most recent version of firmware, and asks if I want to install the same version.
I Want to rollback to 8.1... any ideia?

 

[charlatan1978]

It will rollback to 8.1. The firmware will be the same, the operating system is software.