If you had removed all of their collision they would just fall through the world, so clearly something still has collision.
Either way that is not the proper solution to this problem. You’ll want their capsule’s collision setting to not block whatever collision channel it is set to (probably Pawn), so they can pass through each other, but they should still block Static Mesh so they don’t fall through the floor.
If it still doesn’t work, you may have to uncheck “Can ever affect navigation” in the component settings of any components that have collision.