How can I get medical bills from atrium health off my credit score? It’s already gone to collections and they aren’t willing to cooperate.?

You can pay them.  That is how you get them removed.

Items in default can stay on a report for up to seven years from the time they first appear, not from when the debt was first owed.

Cooperation is a two-way street. Pay what you owe and they may remove the negative info.

You don't.

You owed money in 2018 which you never paid. Your non-payment was correctly reported to the credit bureaus. Eventually Atrium gave up on ever collecting and sold your debt to a collections agency; everything after that point is irrelevant to your credit score.

The best you can do is add a comment to each of your own credit reports justifying why you didn't pay.

You cannot get accurate information removed from your credit.  Eventually the information will become old and fall off your credit due to age.  All you can control is whether or not that collections item shows as paid or not. 

"...and they aren't willing to cooperate."

Have a nice day in Trollville

Do you owe the money? You can contest a bill you think is in error, but if you really owe it, the way to make it disappear from collections and stop impacting your credit score is to pay it off.