Inspired by Can mage hand be used to trip an enemy who is running away?, and possibly an alternative solution to that problem.
My bard is an obnoxious jerk who enjoys a laugh at anyone else's expense. The gods saw fit to equip bards with the gift of Mage Hand. Can he use it to yank someone's pants down to cause them public embarrassment?
You can use your action to control the hand. You can use the hand to manipulate an object, open an unlocked door or container, stow or retrieve an item from an open container, or pour the contents out of a vial. You can move the hand up to 30 feet each time you use it.
Pants are, of course, an object. Unlike many spell effects (such as Catapult or Enlarge or the "ignites flammable objects" language in spells like Fireball), Mage Hand has no restrictions about being used on objects that are worn or carried.
The Arcane Trickster's Mage Hand Legerdemain enhances Mage Hand by allowing it to access the contents of containers that are being worn or carried, which implies that the containers themselves, or worn or carried objects in general, are already valid targets.
Related but distinct: Can Mage Hand grab opponents' items? (we're not actually trying to lift anything off them, just reposition it).