This is the worst part. It does not twist off manually- even with a very strong person (not me) trying. Some have claimed they can twist it off. Kudos to them. . . twisting off was absolutely impossible with this mug.

I held it in a vice and cut a small hole in the base right where it is attached to the mug using an oscillating saw. This was overkill of a tool but it worked.

Do not cut where I did. I cut on the side opposite of the "Ember" logo just lateral to the handle. This was NOT the best option, but I was lucky (see step 2). If I were to do this again, I would cut on the other side of the handle just between the handle and the "r" of "Ember" logo.

Wherever you cut, make sure it is shallow and angle up towards the opening of the mug to avoid the circuit board.