Attacking overlocking with your seam ripper can be one of the most frustratng tasks when sewing....until that lightbulb moment when you discover you only need to cut the needle threads.
This pic shows cutting the needle threads with an unpicker. using this method you have to do this every few threads. But the loopers do just fall away.
My favourite method possibly works best on thinner fabrics. Near where I started sewing I cut the needle threads with an unpicker like the first picture, do that either side of where your sewing begins. Then move a few stitches along, put the spike of the unpicker under the needle threads, but don't cut them, gently pull the threads so the cut ends pull through leaving tails. You might need to do this a couple of times. Once you have thread tails long enough to hold on to, pull them and slide the fabric just as if you're gathering fabric. Keep pulling and sliding and eventually the other end of the needle threads will release the looper threads allowing them to just pull away.
Even if your thread breaks or its a bit tough you'll probaly be able to remove a few inches. Cut the needle threads a few inches further along, pull them out, then make new thread tails and do the next section.