Recently had a situation where I wanted to immediately reclaim the free space after deleting a vast amount of data from a disk with Data Deduplication enabled.
After searching through the Microsoft Docs I came across this page: Microsoft Docs Reference
Scroll down to ‘Garbage Collection jobs’.
I ran the below PowerShell command to start the Garbage Collection task. Replace ‘E:’ with your drive letter.
Start-DedupJob E: –Type GarbageCollection