Stick the axle into the bearing to use as a leverage bar. You need to rotate the bearing 90 degrees on a horizontal axis to remove them from the carrier. You’ll see the slot on the carrier where it pulls out, that’s your pivot point.
You can set/bolt the bearing in the hanger on the chassis and stick the axle in the bearing sleeve, pull up, or push down. Or you can do it off the chassis. I usually just stand the axle up vertically, slide the bearing on the top of it and tap the carrier on the top or bottom with a rubber/plastic mallet to get it to rotate.