wind down

Short definition from Wiktionary

Verb

1. 1
   To lower by winding, as with a crank or windlass.
2. 2
   To unwind.
3. 3
   To shut down slowly (by degrees or in phases).
4. 4
   To slow, as if coming to an end; to become calmer or less busy.
5. 5
   To relax; to get rid of stress; to destress.