Fireplace and Chimney removal
Some people want to remove either a chimney stack or a chimney-breast, or both:
because they don't want an open fire
because the chimney is damaged and removal is seen as a cheaper solution
to solve a damp problem
to make more space inside the house especially in more smaller rooms.
If you still want to remove part or all of a chimney the options are:
remove the chimney stack to below the roof
remove the chimney-breast from one internal storey
remove the chimney-breast from all rooms
remove the chimney-breast from the attic or loft

In S
Most chimneys are free standing. That is, none of the roof structure or floor joists are tied into the chimney brickwork. You could remove the chimney but it should be removed all the way up to the roof. I would not recommend only removing the ground floor chimney breast because the remaining brickwork would have to supported in some way or it would collapse.
If the chimney stack is removed to below the roof, the roof timbers must be extended to meet the wall, and matching tiles or slates found to fill the gap.
If only part of the chimney breast is to be removed, the remaining brickwork above must be supported with an RSJ (rolled steel joist) supported on gallows brackets; a wooden beam is not normally satisfactory.

If a chimney breast is removed in a room, you must decide whether to replace the hearth; if you do this the joists and floorboards must be extended. Damage may be caused to the ceiling of the room below.