There are a variety of reasons for removing the oil pan from your car - sometimes you may need to get in behind the pan to perform some other repair or maintenance, or you may just be servicing the oil system itself. Whatever the reason, knowing how to remove the pan is a useful skill for any amateur mechanic.
First locate the pan, using your owner's manual as a guide if necessary. Nearly every car has the pan located in a different place - some may be very easy to remove, while others will require that you jack the car up in order to access it. If you do use jack stands, be sure to block the wheels and apply the parking brake before getting to work.
Place another pan underneath the oil pan and then remove the plug to drain the oil out of the vehicle. This is a good opportunity to do an oil change as well if your car needs it. Look around the pan and see how its attached to the vehicle - it might be mounted to the motor, or you may have to remove a cross member to gain access to it. You'll need a ratchet and socket for this, potentially one with a long handle depending on where your pan is located.
Keep that ratchet in hand, as you'll also need it to remove the bolts that attach the pan to the engine. You may need to use a swivel socket in order to get in there, as it can be tight quarters in this part of the vehicle when it comes to maneuvering. Be sure to set any bolts aside so you know how to reattach the pan when the time comes.
Once you've removed the bolts attaching the pan, you have to knock it free. Strike the pan lightly with a rubber mallet in order to dislodge it from the engine. You may have to strike it a few times to get it out. Alternatively, you might also need to employ the use of a pry bar in order to free the pan from the engine.
If you have a gasket scraper, now's a good time to remove some of the old gasket material that has built up on the pan or engine block. Be sure to do this gently, as you don't want to scrape and damage the surface of either part.