You need to siphon it out. You'll also need several gas cans if the tank is full.
empty gas out and drop tank
The 2001 Buick LeSabre's fuel tank holds 18.5 gallons as found on http://consumerguideauto.howstuffworks.com/2001-buick-lesabre-3.htm
In the gas tank?
In the fuel tank. Drop the tank. Hopefully its almost empty or else its really heavy. You will see the pump module on top of the tank.
ITS IN THE GAS TANK!
in the gas tank
Inside the fuel tank. To get to it, you have to drop the tank.
In the fuel tank
17
18 gallons
18 gallons.
Inside the fuel tank