I just buy the small inexpensive ones with the narrow tip and pitch them when they get dull. I usually unsew seams by using my narrow pointed scissors. I cut the bobbin thread every 3 to 4 stitches and then pull the top thread to remove the stitching. If the stitching line is really tight with tiny stitches, I pull the 2 fabrics apart to expose the thread and touch a little eye brow trimming wand to the thread. I got the tip here on QB to buy the eye brow shaper. It has a tiny razor blade with a mesh guard to trim hair without cutting yourself. It works well to cut the thread without cutting the fabric.