The Apostle Paul is instructing a fairly new church on how they are to live the Christian life. To be able to accomplish this they would have to start with removing the old way of life.
“Put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, and to be renewed in the spirit of your minds, and to put on the new self, created after the likeness of God in true righteousness and holiness.”
Ephesians 4:22-24
Previous to these words, he stated the primary reason for the change. It was the precursor to being fully changed into the image of Christ.
“To know the love of Christ that surpasses knowledge, that you may be filled with all the fullness of God.
Ephesians 3:19
We must get rid of the old to make room for the new. We cannot have both.