If a device is no longer required for use by LVM, you can remove the LVM label with the pvremove command. Executing the pvremove command zeroes the LVM metadata on an empty physical volume.

If the physical volume you want to remove is currently part of a volume group, you must remove it from the volume group with the vgreduce command, as described in Section 4.3.6, “Removing Physical Volumes from a Volume Group”.

# pvremove /dev/ram15
  Labels on physical volume "/dev/ram15" successfully wiped