How do you remove a load bearing wall?

Support the load whatever it is, roof, second floor, generally by putting a temporary beam under the joist inside of the existing wall, tear the wall out and put in a beam to carry the load. How big the beam needs to be depends on what the load is and how long the span is. Support the beam on each end and remove the temporary beam. These are the general steps, each project is going to be slightly different and has to be figured on it's own.