The quickest way to remove concrete would be to cut the concrete to be removed with a diamond blade concrete saw along with water running where you cut at all times; keeps the dust down and keeps the blade cool.
I've been using a 60lb electric jackhammer for years. Takes a little time but it eventually spider cracks the concrete.
Those 90lb air jack hammers you need to pull a compressor behind your vehicle are the way to really make mince meat of the job. They make a relatively lightweight air hammer that destroys concrete.
I speak mainly from past experiences, try not to do that type of work anymore.