When there aren't any running vms on this host you can shutdown and disconnect it from san then reboot and remove all the vmfs volumes from it.
After the next shutdown you connect it to the san again and restart it. That should work.
Removing all the VMFS volumes is a non-issue, since the host doesn't recognize them. I removed the ESX server's HBAs from the host group on the SAN and rescanned them from the VI client. Sure enough, the ESX server saw no LUNs. I rebooted, then added the HBAs to the host group again, rescanned, saw nothing, then rebooted again. Once again, the ESX server sees the LUNs but not the VMFS filesystems.