If you just need to thin provision the data disk then you can create a new thin provisioned disk and then move the database and log paths but note that this does require downtime.
Other options include doing a Storage vMotion in VMware and configure the destination disks to be thin provisioned or use the Microsoft Hyper-V equivalent.
Least downtime will be creating a DAG and then just moving the active mailbox database copy. Moving mailboxes can be done also but this will require more downtime than the DAG. These two options do you require you to build a new Exchange server and if you're
using Server 2012, you don't need server enterprise licensing but you will do if you're using Server 2008/2008 R2.
Do also note that dymanically expanding disks are not supported. See here: https://technet.microsoft.com/en-us/library/jj126252(v=exchg.141).aspx.
Ideally if you need to shrink the disk to reduce SAN usage then create a new thick provisioned disk and extend as needed.
Thanks.