Yes, We can decrease VMDK ( VMware Virtual Machine Disk ) if somehow it got increased more, the steps are :-
1. Make sure unallocated space is there at OS end , if not shrink the Disk from OS end as per your need.
2. Login on ESXi Host with SSH via Putty session
3. Go to datastore with cmd.
# cd /vmfs/volumes/datastoreName/VMFolder/
4. Now you need to identify VMDK Descriptor file for which you want to reduce size >> Note down size in-front of RW for “flat.vmdk”
# Cat VMName.vmdk
5. Edit descriptor file (.VMDK)
# vi VMName.vmdk
6. Change no. as you need space (in front of RW)
For Example disk size is 125GB and you need only 60 GB disk then calculate like this:-
7. Save Descriptor file (.VMDK) with :wq!
8. Migrate VM from one host to another host.
9. Validate VMDK Size on Summary tab of VM
10. Validate Disk Size at OS end too.
, That’s it 🙂