Yes. To delete an entire device you must first navigate to the 'View' tab within the SpiderOak application. Next, select the device you would like to remove and then click the remove button ('X') in the menu bar. When prompted if you would like to purge the device and all its contents, choose yes. This will remove the entire device and all of its contents.
Please be aware that you cannot delete the device that you are currently using. If you attempt this, SpiderOak will give an error. You must be using a different computer which is part of your SpiderOak account to delete a device.
You also cannot delete the only device in your account. If you want to delete all devices from your account, you will have to leave one device, then create a new device on any computer. You can then use the new device to delete the last remaining old device.
If you delete a device and do not immediately see your storage size reduced, this could be happening for two reasons:
Sometimes it takes a few minutes for SpiderOak to update itself with the servers. In this case, the size will adjust itself automatically within a few minutes.
If the data on this device was also stored on another device in your account, the data was deduplicated so that only one set of files was taking up space in your account. As long as you have one full set of files, they will continue to take up the full amount of space. For more information see https://spideroak.com/engineering_matters#storage_saving.