Guide to Octoprint
Octoprint is described by its creator as being somewhere between a "baby monitor" and a "remote control" for 3D printers. It allows for monitoring and control of prints remotely.
From this page, you can pause the print or cancel it if needed.
The camera is at an angle that does not permit easy assessment of small blemishes in the print, but it should show any catastrophes that require cancellation.
Canceling an object
There are two ways to cancel an object. To get a list of objects, click on the hamburger menu on the right and select the Cancel objects tab. This is hard for us since we use so many repetitive objects that are named non-intuitively.
More intuitive is the GCode viewer page. Select the GCode Viewer tab and allow it to process the gcode. It will present you with orange dots. Note that the orange dots are not exactly over the object they represent, so use your judgment on which object to cancel. Note the red markings on the image for examples.