OK when it comes to gang members you just can't wake up one day and say "Hey I'm retired from the life that's it. See you later."

There are rules.

So I see these guys retiring from the mob on the other hand and it seems like if you decide that you want to retire you can just walk away at any moment.

Why is this allowed? Especially if you are still active and making a profit for them? I would think a boss would have to approve this decision yes?