First of all I think it is only removal we need to provide for.

If Parliament does introduce legislation to allow removal from the Line of Succession, then I would hope that would set out the appropriate circumstances and valid measures or routines to be followed to remove someone.
In other words, such an Act would not deal with any specific person.
It would lay down circumstances, conditions, authorised decision maker or makers, and the mechanisms or procedures to identify and remove a person.
The Act would exist to enable a removal by a relatively simple - and swift - process.