how to remove 5 feet of concrete ?

5 feet does not sound like a lot to make renting the jack hammer worthwhile. you can put on your glasses and face mask, dampen the area with water to keep the dust down, and go at it with a long handled sledge hammer. For tidy bits and neat corners, you can use the chisel and sledge together, get a stone or concrete chisel please.

Once you get it started, you will find it goes pretty quick, and it will help buff you up too!

are you talking about 5 feet THICK concrete?????? No one would put 5' thick concrete in a floor. The hoover dam is 5' thick. If it is 5' thick, forget the jack hammer or anything else, you aint getting through it

This sounds like something you should pay to have done. There are plenty of do-it-yourself projects you can do, but there are some things that it is better to hire out. Rethink your options.

Hammer jack is the only thing I can think of. Also check with your local church, sometimes the Men's Ministry will help others with Do-it yourself projects.

You can rent a jack hammer at your local equipment rental store. Wear eye and ear protection when using it.

a bigggggg hammer!!!!!!!!!!!!