Puppy Let go!!!

I have a new pup. A find/stray of about 5 weeks. I think he's pure black lab, but maybe not.

Here's the problem: He bites or tugs on objects, and he's got teeth like needles.

My question is this: When he's got something (possibly me) in his mouth, how do I get it out? Some examples include my fingers, or more commonly, the hem of my skirt or pants. Obviously, hitting him is out of the question, but as a practical matter, how do I get something out of those teeth? Even when I go to pet him, he snaps at me with the teeth.

I have tried yelling "Ouch!" when he nips.

People say, "Take it from him!" That's fine as advice, but this little dude doesn't let go. One scenario would be me taking him out for a late-night walk, and he grabs on to my pajama bottoms when we come into the house because he wants to play instead of go to bed. I can't shake him. How do I recover my jammies? A tug-of-war just encourages him.