Run this script :
That gets you all the mac addresses for the hosts in the cluster.
Now follow what is in this KB:
vmkfstools -D /vmfs/volumes/UUID/VMDIR/LOCKEDFILE.xxx
run that on the vmdk file you cant delete you’ll get an output like
Lock [type 10c00001 offset 233148416 v 1069, hb offset 4075520
gen 57, mode 1, owner 570d1952-3933cca0-906d-bc305bf57cf4 mtime 8947925
num 0 gblnum 0 gblgen 0 gblbrk 0]
Addr <4, 552, 50>, gen 1050, links 1, type reg, flags 0, uid 0, gid 0, mode 600
Now match value in RED against the list you have in that csv output you got earlier.
You will find the host that maintains the lock, log onto that host and see if there is a VM in an unknown state, if there is…… delete it.
If not log into the datastore from this host and delete the lcoked file and you should be able to just fine.