Put on protective goggles, work clothes and work gloves. Dust and debris will fly up when you cut the porcelain, which is a more-efficient method than breaking the it into pieces. If you strike the porcelain before loosening it, there's a higher probability of damaging pipes and other fixtures in the wall behind it. Cutting the slab out is more efficient for this reason.
Showers typically last for years and don't get renovated in a home very often. However, if you don't like the look of your shower, you don't have to be stuck with it. Renovating or replacing a shower requires effort, but it is possible to do it yourself if you have experience or with the assistance of a professional. Before you can add new surfaces and fixtures to a shower, you need to remove the old ones. Removing a porcelain slab from a shower requires some care and basic equipment.
Position a keyhole saw against the wall next to the slab. It is usually more effective to cut around the slab than through it. If you need to cut through the slab itself to remove it, use a diamond blade to prevent your saw from getting worn out or damaged.
Run the saw down the wall next to the slab to loosen the porcelain. Follow the perimeter of the slab with the saw, using caution to prevent going too deep into the wall. Cut the slab free without going deep enough to nick any pipes, studs or plumbing fixtures with the saw blade.
Insert a crowbar into the space created by the saw to wedge the slab away from the wall.
Pull out the slab and backer board. It will be heavy so you'll likely need assistance. Once the slab is loose, break it up with a hammer if necessary to make removal simpler once the risk of harming the material behind the slab has been removed.