When you're finished marking up a scene with Grease Pencil, you can clear all sketches before handing off the shot. You can delete all grease pencil frames in the scene, or delete only the frames on a specific camera.
(This can occur if you cut the last Grease Pencil frame in a sequence, or if you have created Grease Pencil frames on a temporary camera created with Panels > Look Through Selected.)
The following warning displays next to the Command line to indicate that Grease Pencil nodes are removed.
// Warning: line 1: Removing grease pencil node network