Pretty sure he means debuff as-in remove the buff.
It wouldn't restore the item you already used with the remaining time... that would just be silly.

But say if someone used an Ice Latte to run away, but you cannot deal damage while under these effects, they could debuff it and the effects (both positive and negative) would be removed allowing them to deal damage again without having to wait for the effect to wear off automatically.

You're correct in your understanding of what he was saying, but incorrect in your use of the term "debuff".
A buff is a positive effect, like a LW or coffee.
A debuff is a negative effect, like bleeding, or being blinded by a concussion grenade.

The act of removing a buff would be called cancelling.

I'll see about implementing something similar to the ideas in this thread over the weekend.