For future hatches, once they start a full zip (like more than an inch or so of actual zipping) they should finish within an hour, 90 minutes at most. If they stop part way, you can break the “cap” off, but let them kick out of the bottom part of the shell on their own.
The pic looks like just the left over gunk, it should dry up and fall off on its own, but if it starts dragging it around by like a string, you can snip it with scissors. Just do it away from the body, leave a little bit attached, but remove the main bulk of it. What you leave will dry up quickly.