If you've ever tried to lift an internal door, you'll know they're much heavier than they look. Because of this, it's always a good idea to use tools to your advantage! And one of the best tools to use for this job is a flat pry bar. This tool is designed to remove nails and floorboards, but it can work wonders when you want to remove a door, as it fits perfectly underneath.
The design of the pry bar also means that you can put your foot on the end for extra force, and you can even put something underneath the bar if you need some extra help to remove it.