You're lucky. All the big sites like ESPN, Fox and Yahoo have already removed the background for you.
All you need to do is get a facepack size template, download the player photo(s), then resize your source picture using 'percent' (so it doesn't stretch/look weird).
Then you need to create the files that go into the game using Facepack_creator.
That's really all there is to it if you want to do facepacks for NHL/AHL in 2019. That's why it's hilarious when someone complains about the huge task of making NHL facepacks nowadays. It's time-consuming and boring, surely, but the days of you removing the background by yourself are literally gone. Of course you can edit the photos if there are pixels that haven't been removed properly.