With a Toto toilet, the procedure for removing the hinge bolts for the seat isn't much different than the procedure for other toilets. The only difference is that the seat is probably attached with the metal bolts and rubber sleeves that Toto includes with its products. If you have a Toto washlet, which is a heated seat that includes an automated bidet, the procedure appears more mysterious because the washlet completely covers the bolts. Once you move the washlet out of the way, though, you'll find the same metal bolts and rubber sleeves.
Removing a Conventional Seat
Locate the two covers that hide the seat bolts behind the toilet seat. Each one is hinged, and you have to pry the side opposite the hinge to snap the cover up and expose the bolt. You may be able to do this by hand, but if not, use a flat-head screwdriver.
Unscrew each bolt by turning it counterclockwise with a No. 2 Phillips screwdriver. The bolts rarely stick, because friction holds the rubber sleeves into which they fit securely against the holes in the toilet. If the sleeve turns with the bolt, though, you need to hold it steady from underneath the toilet.
Clamp a pair of locking pliers onto the sleeve -- it's black, and it extends about 2 inches underneath the bowl. Turn the screw again -- the sleeve will turn with the screw until the handle of the pliers contacts the bowl and prevents the sleeve from turning any more. You'll then be able to remove the screw.
Lift the seat off the bowl after removing both bolts. Grip the top of each sleeve with pliers and pull the sleeve out of the hole in the bowl to complete the removal procedure.
Removing a Washlet
Unplug the washlet, turn off the water supply to the toilet and unscrew the water connection to the toilet with a wrench.
Reach your right hand around the side of the washlet and locate the release button. Push the button in while you pull the washlet toward you. The washlet will slide right off the mounting plate on the back of the toilet.
Unscrew the bolts holding the mounting plate using the same procedure for removing the bolts holding a conventional toilet seat.