If it's required.. it's going to show. That's simply how it works.
There is an add-on for profile completion that may allow you to force it after registration... but by default.. you get what you get.
Is the field shown as "required" in your custom field setting?
If the field is required.. it's going to be shown no matter the "show during registration" option. If it is not shown as required, then it should only show if the option you highlighted is selected.
If it's required.. it's going to show. That's simply how it works.
There is an add-on for profile completion that may allow you to force it after registration... but by default.. you get what you get.