To put off something is to do away with a thing, discard such thing totally. When one puts off the old man scripturally, it simply means doing away with sinful things of the past. The past here is talking about all forms of unrighteousness and iniquities before one gives his or her life to Christ . To put off the old man also means such person is trying to forsake all forms of corrupt nature the individual has been in before such person surrenders his or her life to Christ, no wonder the bible reveals it in (2nd cor. 5:17) “Therefore if any man be in Christ, he is a new creature: old things have passed away; behold, all things are become new”.
An old man scripturally, gets involved in old things which is totally against the will of God. In order to do away with old things, an individual needs a total and constant renewal of mind. Hence, such individual becomes a new man in Christ. (Ephesians 4: 22-24). As Christians, we all need to learn and receive the grace of putting off the old man in us at every point in time and seek the new man (col.3:9-10).
In conclusion brethren, to put off the old man is to do away totally with the devil and his tactics in brainwashing us to go back to the sins we have earlier renounced. This however can be achieved with constant fellowship with the Father and I pray as we continue the heavenly race, the ability to always resist the devil the Lord will grant us. AMEN