I use my tweezers to unscrew those threaded holders.
Selecting the right size tweezers and with a steady hand, it usually unscrews easily.
Be careful not to damage the thread, and... mind you're fingers
Usually there is not much resistance in there, remember not to overtightened them either.
Or, if you plan to do this more often, i suggest you make a set of fixed tools to fit various sizes, think of a big screw driver, made of some tough plastic, with a wide notch in the middle or more like a straight spoon with a notch.
Use a hard plastic like ABS or polycarbonate.
Molding some composites for more durable tools would be an idea too.
Good luck!