Make sure there are no instances running:
$ nova list
If there are, delete them:
$ nova delete devstack
Make sure the only networks that remain are public and private:
$ nova network-list
If there are other networks, delete them:
$ nova network-delete hackspace
Make sure there are no volumes remainig:
$ nova volume-list
If there are, delete them:
$ nova volume-delete 455ec395-cfab-4319-bbf0-1d061c14a7e8
Make sure there are no images you created remaining:
$ nova image-list
If there are images you created, delete them:
$ nova image-delete web-snapshot
Make sure there are no containers remaining:
$ swift list
If there are, delete them:
$ swift delete hackspace