The Cobber lights utilizes a tool-less magnetic mount, with a clip in channel to keep the light secure.
Please see the Cobber user guide here in order to understand the mounting process.
You can simply reverse the mounting process to remove the light - push in lightly on the light, and slide it upwards to disengage the light from the mount. Sometimes it can be easier to push from the tabs on either side of the mount (the parts that hold the strap).