What does it mean that believers are dead to the desires of the old Adam?
Believers are dead to the desires of the old Adam because they have let old Adam be crucified with Christ. This death is not something they work for or attain; it is the power of God exercised in His saving salvation. By identification with the crucifixion, they are freed from old Adam's desires and will live with Him.
Les explains that those who have let old Adam be crucified are now dead to the desires of that old Adam. This is not something you work for or try to attain; it is all part of the power of God when it is exercised in His saving salvation. He connects this to verse 8, where being dead with Christ by identification with the crucifixion means we believe we shall also live with Him. Les emphasizes that the resurrection is fundamental to our faith, and that Christ died unto sin once to rid us of old Adam, once for all, satisfying for all eternity.
For he that is dead is freed from sin.