The solution is to 'hand the man over to Satan' which means to put him from the sphere (realm) of God (His Temple which is the Body of Christ, the Church) and put him (or surrender him) into the sphere (realm) of Satan (the world) - in other words, Paul recommended they cut him out of fellowship in the Church.

Notice that the main aim of this is the man's eternal salvation. If he were to be truly repentant and not full of pride then he could be accepted back into the fellowship. In Jesus' teachings about such men He says that Christians should treat them a 'tax collectors etc' which means that they treat them as non-believers. How are non-believers to be treated ? As ones who need the Lord with all love and prayer! But there can be no real fellowhip with such people who have not the Spirit of God.