I wouldn't advise taking that fireplace down unless you are knowledgeable of the work that needs to be done.Taking down the fireplace is a job you can do yourself, but it will take some time and you must use extreme caution. Demolish your fireplace from the top down, one brick at a time. Erect or rent a scaffold and work from it. Make sure that the scaffold is equipped with stable flooring and safety rails and that it is securely attached to the building.
In other words looking at the drawing provided and the heating supplies locations you can clearly see that there is a # of joists resting on the side wall of the fireplace.
This structure would have to be reframed on both levels in order to properly support floor and ceiling joist which would be left free if the side walls where ever removed.
In addition opening on the roof would have to be addressed afterwards.
My suggestion would be to incorporate that fireplace in to the design somehow else.