Drywall – Moving and covering light fixtures in bathroom

A sawzall should make quick work of this. If you don't have one and know no one that does, they can be rented. There are also handles that clamp onto hacksaw blades so you sort of have a small, manual sawzall. It will take some work, but you will be able to cut enough that the remainder can be twisted off or chiseled aside.

If done carefully and methodically, a dremel tool can do much of the work without starting a fire. Try to direct the cut so that the sparks are ejected mostly downwards. Stop often and check the area for signs of burning. Have a spray bottle handy to quench any embers, as well as a fire extinguisher just to be safe. When finished cutting, spritz the area with water and check the area frequently for the next hour for any signs of embers developing.

Finally, depending on the finish, cutting and patching the ceiling is not that big a deal, then you can ensure the new box is properly supported instead of relying on the little tabs of the old work box and ceiling material for support.

Sounds like you pulled out some butterfly anchors instead of unscrewing them, or even large molly type.

What I do in situations like this is to install a decorative BOARD behind the towel rack or toilet paper holder, on the surface of the drywall, which screws directly into studs. This can simply be a piece of 1X4 with routed or finished edges, or baseboard or crown molding in 3 inch or larger width, painted white or the wall color. If desired, continue around the room at a single height, making this look like a standard feature similar to the top of chair rail decoration.

Install this with screws long enough to reach into the studs behind the drywall, I typically use 3 inch long self drilling screws. If you don't want the screw heads to show, spackle over them or use caulk before painting. The baseboard or molding typically can be found in 3 inch or larger widths, cut to length as needed, providing enough room to install the racks or fixtures on it. The racks can then can screw into this. This eliminates any unsightly holes or bad patching that might be present, as the board goes right over them. Studs are typically 16 inches on center, use a stud finder to locate them. For the toilet paper holder, if the board is attached by screws into one stud firmly, and the other end is installed with butterfly anchors, it should never come off the wall.

The exception would be a block wall behind the drywall, which probably would have furring strips holding it up. You'd then be able to use a drill and concrete anchors with longer screws to hold up either the board, or the racks themselves.