====== Delete multipath device ======

  * Check the fstab for the devices that has to be removed.
  * Be sure to unmount them!
  * Check that you have uncommented or removed all ref. in /etc/fstab to the SAN LUN (Volume Group / Logical Volume)
  * If LVM is used:
a.	Remove the logical volumes
  lvremove
b.	Remove the volume groups 
  vgremove
c.	Remove the physical volumes
  pvremove

  * Remove each path to the device from the SCSI subsystem. To do so, use the command echo 1 > /sys/block/device-name/device/delete where device-name may be sde, for example. 

(Another variation of this operation is echo 1 > /sys/class/scsi_device/h:c:t:l/device/delete, where h is the HBA number, c is the channel on the HBA, t is the SCSI target ID, and l is the LUN)

a.	Do this for every device name in the mpath that has to be removed:

b.	Run multipath –ll to see the devices
Eg. :
  echo 1 > /sys/block/sdck/device/delete
  echo 1 > /sys/block/sdcw/device/delete
  echo 1 > /sys/block/sdi/device/delete
  echo 1 > /sys/block/sdu/device/delete
  echo 1 > /sys/block/sdce/device/delete
  echo 1 > /sys/block/sdcq/device/delete
  echo 1 > /sys/block/sdc/device/delete
  echo 1 > /sys/block/sdo/device/delete
  
  * If the device uses multipathing, run multipath -l and note all the paths to the device. 
NB! Note the wwn before you delete the multipath!

  * Remove the multipathed device using multipath -f device.

  multipath –f mpath0

  * Ask SAN guys to remove the LUN(s).
  * Reboot and follow startup from ILO


Thanks to Mikkel Arnberg for the input to this article.

Reference:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/removing_devices.html#clean-device-removal