Polearm Master (PHB p. 168) gives you the ability to situationally make a bonus action attack:
When you take the Attack action and attack with only a glaive, halberd, or quarterstaff, you can use a bonus action to make a melee attack with the opposite end of the weapon. This attack uses the same ability modifier as the primary attack. The weapon’s damage die for this attack is a d4, and it deals bludgeoning damage.
The optional Disarm rule (DMG p. 271) allows a weapon attack to disarm rather than do damage:
A creature can use a weapon attack to knock a weapon or another item from a target’s grasp. The attacker makes an attack roll contested by the target’s Strength (Athletics) check or Dexterity (Acrobatics) check. If the attacker wins the contest, the attack causes no damage or other ill effect, but the defender drops the item.
Can you Disarm using the bonus action attack provided by Polearm Master? (obviously forgoing the damage roll).