Vasana kshayam means my identification with vasanas, which are expressed as desires cum thoughts decrease. This makes the vasanas as jada vritti that comes into my awareness rather than making me to act according to them. The fulfillment or expectations from the actions decreases as I realize my fullness.To get that dis identification one needs a relatively pure mind clear of raga dveshas where the reflection of consciousness can be seen for what it is rather than clouded by rajas or tamas.