One of my players rolled a Thief rogue. At level three they get the Fast Hands feature:
You can use the extra action granted by your Cunning Action to make Dexterity (Sleight of Hand) checks, use your thieves’ tools to disarm a trap or open a lock, or use an object in the environment.
The player asked mid-fight to use a Sleight of Hand check to disarm a foe. Since this isn’t clear in the PHB, the discussion slowed down the fight considerably. To end this discussion, I ruled that the player could make a Sleight of Hand check contested by the enemy’s Strength (Athletics) check.
I still find it hard to see how a Sleight of Hand check could work to disarm mid-combat, since there’s no way you’d be able to "sneakily" take someone’s weapon out of their hands while fighting.
There is an optional "Disarm" rule as listed in the DMG, which uses a weapon attack against an adversary’s Dexterity (Acrobatics) or Strength (Athletics) check to determine whether or not a disarm action succeeds.
Could a Thief rogue disarm an enemy in combat using Sleight of Hand as a bonus action?