Photoshop Timeline - easy way to delete unused layers?

Thanks for your response. I considered delete >> hidden layers, but the issue with that is in how those layers relate to the frames in the animation timeline. When I import video frames to layers, one layer is created from each frame of the source video. That layer has a correponding frame created in the image's animation timeline. So at any given frame in the timeline, the one layer associated with that frame is visible and all the other layers are hidden. Deleting hidden layers results in all layers but that one being deleted, so all other animation frames become blank. In the attached image, I show how a selected frame in the timeline makes its layer visible, and then how selecting another animation frame makes that frame's layer visible and hides the previously visible one. At the bottom is the result of using delete >> hidden layers.

I deleted frames from the timeline, but their corresponding layers remain, and are unused (never become visible over the course of the animation). It seems likely that no shortcut way exists to weed out these unused frames, beyond deleting them manually as I delete frames from the timeline.

Again thank you for your suggestion, and if anything else comes to mind upon my clarification of the issue, or if you need further clarification, please let me know.