you didn't mention if you are on a SAN (VMFS), a NAS, VSAN, or VVOL. The locking mechanisms are different for each. On a NAS, you are looking for hidden files starting with Period (.), that is the easy case, delete the files from a putty session. For SAN it is a lot more of a problem, look for KB10051: https://kb.vmware.com/kb/10051