Yes, you can remove IX-ONE Buttons if you have a Premium or Platinum code(s).
Depends on the button and its content. Even if it allows to change in some cases, we strongly discourage you to do so to avoid affecting the link between the IX-ONE and ELI database.
There is no maximum number of buttons you can have for Premium or Platinum codes, however we recommend 4-6 Custom Button on top of 6-8 Auto-populated ones from IX-One. Click to view https://eli2.us/s/rz66zo65