Run the command esxcli system coredump file list until get a true value for both parameters Active and Configured.
[root@esx:~] esxcli system coredump file list
Path Active Configured Size
------------------------------------------------------------------------------------------------------- ------ ---------- ----------
/vmfs/volumes/xxxxxxxx-xxxxxxxx-xxxx-xxxxxxxxxxxx/vmkdump/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.dumpfile true true 3740270592
Then run the following two commands to remove de the dump file:
[root@esx:~] esxcli system coredump file set -u
[root@esx:~] esxcli system coredump file remove -f /vmfs/volumes/xxxxxxxx-xxxxxxxx-xxxx-xxxxxxxxxxxx/vmkdump/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.dumpfile
Now you can remove the vmkdump folder.