Midland will also delete even if you settle for less than the full amount. Unlike Portfolio, Midland has the caveat that the debt must be at least two years old. This isn't a problem for OP since they stated that these are from 2017 (I'm mentioning it for the benefit of future newcomers who may not know this).
@Anonymous - the reason you're seeing mixed score results when paying collections is due to the reporting tendencies of those collectors. Some slap a collection on your reports and just let it sit. In your case, if they did that and you paid it today, you'd lose points when they update your balance to zero because they hadn't been updating it all along. It appeared to be a stagnant old four-year old debt, and when it updated it was "refreshed" in the eyes of the algorithm, causing a loss.
Other, might I say more malevolent collectors will update the bureaus monthly, kind of like saying "hey, yeah they still owe us, just like last month, and the month before, and the month before that, and..." - by doing that, their account always appears to be new to the algorithm. It doesn't cost you points each month but it does suppress your scores. However, when you pay and they update it to zero, it's just another update in a long string of them and therefore the update doesn't harm you.
Law states that once a debt is paid or settled, it must be updated to reflect that, and then the updates must stop. That's what @calyx meant above by it being able to begin to age and fade back. The longer the amount of time that passes between the final update and now, the more your scores can heal. And definitely allow one card to report $10-15 while the others deport zero. That should gain you an easy 10-15 points.
Good luck and follow up anytime with further questions!
