Web Interface
On the left hand side menu, go to Volumes > Volumes
Click the drop-down menu on the right-hand side (in
Actions
column) and selectMANAGE ATTACHMENTS
Click
DETACH VOLUME
Command-line
openstack server remove volume <server-id> <volume-id>
$ openstack server remove volume 6b2bedc4-9d8e-4bf3-be63-1dd49bc2e188 2d61791d-5f52-46e1-81ac-05221c308fe8