How can I delete volumes in error state?

Answer:

Try
nova-manage volume delete vol-XXXXXXXX

Description: (quoted from https://answers.launchpad.net/nova/+question/172482)

If all the appropriate services are not running for nova-volume, a volume will still try to be created, but will be stuck in 'error' state. These cannot be deleted via euca-delete-volumes. You can, however, delete all the invalid volumes from nova.volumes in the DB which will remove the rogue entries.

Examples:

localadmin@nova3:~$ euca-describe-volumes
VOLUME vol-00000001 10 nova error (proj, nova1, None, None) 2011-12-22T05:39:42Z
VOLUME vol-00000002 10 nova error (proj, nova1, None, None) 2011-12-22T07:44:20Z
VOLUME vol-00000003 7 nova error (proj, nova3, None, None) 2011-12-26T04:11:03Z
VOLUME vol-00000004 7 nova available (proj, nova3, None, None) 2011-12-26T05:24:08Z
localadmin@nova3:~$ euca-delete-volume vol-00000001
ApiError: Volume status must be available