Removing a toilet seat is generally one of the easier home repair jobs for most people. In most cases, the job requires nothing more than the removal of a couple of bolts. If you are removing a toilet seat that was put in place recently, this isn't a big problem. Older toilet seats can be problematic, however because the bolts may have become corroded or rusted.
Whether the toilet seat is older and has metal bolts or is a newer one that's equipped with plastic bolts, sometimes the problem can be fixed simply with lubrication. A pair of pliers used in with a wrench to provide leverage can often loosen the bolts after you've applied a lubricant like WD-40 or even plain old cooking oil.
If lubrication does not work, removing the bolts becomes a much bigger problem. Forcing the bolts loose with pliers or a wrench can result in damage to the toilet itself. If you force too much, it is even possible to irreparably crack the ceramic. Rather than taking a chance on this, the next step will remove the bolts in a way that protects the finish.
Use a drill to remove bolts if a screwdriver simply won't work. Not all toilet seat bolts can be drilled loose, but it beats the alternative. The process is the same as for removing any other screw with a drill: Place the proper drill bit into the top of the screw and place the drill on the unscrew setting. If you get lucky, the bolt will at least come loose enough to allow you to remove it carefully by hand. If you get really lucky, the bolt will come right out.
The worst case scenario for removing toilet seat bolts that won't come loose involves using a hacksaw. A hacksaw is the last resort for both plastic and metal bolts. Plastic bolts are generally easier to saw through than metal bolts, but not always. Metal bolts that have rusted or corroded, for instance, may snap easily, while you may be forced to saw entirely through a plastic bolt. The removal of these stubborn bolts can be quite traumatic, so to make it easier next time, keep bolts lubricated and even occasionally twist and turn the bolts to keep them from becoming stuck.