Might be easiest to just create another LUN, format as VMFS6 from the get-go, and svmotion any VMs over and destroy the old one.  ~Chris
I have a LUN (thin) that was VMFS5 and grows to 9TB, but VMware only shows 5TB. Now, I formated (again) with VMFS6 but continue to show 9TB, I tried the command (esxcli storage vmfs unmap -l VM01), but Unisphere continue to show 9TB allocated, and VMware only shows 1TB.  May I have to destroy the LUN to recover the space?  Can reboot or OS upgrade solve the problem?  Thanks in advance
LUN was VMFS5, formated to VMFS6 not unmap