Deleting a video is super easy, and there are a few ways to do so.
Delete videos from your Dashboard
Delete videos from the video's Edit page
Click onto the video you want to delete, then top right click on the three dots and the onto 'Delete'
Delete from the Chrome Extension
If you want to delete a video you've just recorded, you can click the 'delete' button on the bottom left of the Sendspark Chrome Extension preview modal.