If the problem is huge, use mc-edit. I believe it works with the newest version of Minecraft.
But you will be surprised how much time is wasted trying to save time, so I would simply suggest covering it with gravel or stone.
I am afraid there is no easy way to get rid of lava. I am often frustrated by the long time it takes for it do disappear.
Removing the biggest blocks of lava first may cause some of the smaller ones to disappear on their own.