The Ops team said:

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Shrinking

• Virtual disk shrinking is supported when using VMware Converter converting source virtual machine as a machine source (not as virtual to virtual).
  Note: You cannot shrink virtual disks using vmkfstools in ESXi as the hypervisor is not aware of the file system layout and cannot ensure a safe shrink operation.

Before shrinking

• Migrate the data away from the end of the disk consume to ensure the data is not lost (because the disk area is effectively removed). For example, in Windows GuestOS use Disk Management tool.
• Shrink the partition residing within a disk before reducing the size of a virtual disk.
• Non operating system disks users can also add a new smaller VMDK to the virtual machine and copy the data between the larger and new smaller disk using tools within the guest such as Robocopy.

Growing, thinning, and shrinking virtual disks for VMware ESX and ESXi (https://kb.vmware.com/kb/1002019)

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I've seen some other thread somewhere that someone tried the VMware Converter but did not work anyway....

How about creating a new drive, mount it to the file system and copy the content and simply replace it? I know that would be a process that needs to be stopped to accomplish it. It is a just one single drive.