1) Learn how to Get Out First: Cut your engines, tighten up your lines, reel those in that are not hooked.
Then tighten up and drift over - that is back in the direction you came from. Give the lines still caught pull, but also enough time and slack and most will drop off the net, or pull off the net with a little encouragement. Rarely is the barb had time in engorge the twine itself. If your traveling WITH thee tide, it's the same , except that you hold it in reverse to steady your position to retrieve the free lines , then shift to forward and make a sharp u turn , but no so sharp you can't keep the tangled lines free of the boat while turning, and slowly motor back across the net up-tide. It's important to NEVER tight the drag too much. Always leave a little give so you down break the line. I'm sure others can add or fine tune this a bit, but over the years I've learned to free 95% of my gill net hookups, and that's when alone.* When with a crew, one gives directions, the others follow. Make that clear.
2) These rogue or illegal nets are often placed in the highest catch areas - Bloody Point Light, the Channel around 72A, etc. are high density catch areas. The retrieve points long long run gill nets are often multiple. You really have to know what your looking for. My recommendation this: Learn the disengagement techniques, above, first and foremost, and,
B: Beware of leaning overboard flailing a sharp knife in 3 foot seas - statistics say you are more likely to hurt yourself -or- illegally destroy property, whether permitted or not. Get your location data and call DNR later do check licences /location data, if you want.