@FatherGepetto, I will address the anonymous person under your pastoral care in the second person, as though they had asked the question.
I had published several papers with my so-called supervisors ...
Are you claiming they weren't your supervisors? Likely not. So let's call them your supervisors. If you are claiming you weren't supervised, that would be a different question.
... during my PhD, both of whom never actually contributed a single word ... or even ... edited those papers;
Maybe that's true, but - can you prove it?
never actually contributed a single ... idea/method ... or even read ... those papers;
Even if this were true, this is effectively impossible to prove about your supervisors.
anything of value
Perhaps that's what you believe, but - they supervised you. Naturally I don't know any of the details, but a case could well be made that they contributed through you, their supervised junior.
Should that be enough to entitle them to authorship of your papers during your Ph.D.? Perhaps not. But - that's debatable. And many would argue the answer is that it does.
nor would they have been capable of contributing a single word in the first place.
Not only is this effectively impossible to prove, but is also rather slanderous of a claim. People could sue you for saying that - at least in principle.
Bottom line: As far as any adjudicative entity can tell, you might just be lying because you had some sort of a personal quibble with these people; and even if you were to present evidence for the more provable parts of your claim, it would probably not be enough to merit a finding that their authorships should be stricken from those papers.
I'm sorry for the harsh tone, and it's quite possible that you were used for aggrandizement by your supervisors and that they shouldn't have accepted their names being added to those papers, but - this harsh tone is what you'll probably hear when you make your demands.
With respect - I question your motivation here. You write that
I have ... emancipated myself from that abusive relationship
but it seems that you have not quite done so. You are still hung up on relationship with these advisors, not focused on moving forward in your academic career - nor even on improving supervisor-supervised power relations in academia in general - but rather on what could be described as personal vindication.
Even if you were to achieve your goal and remove your advisors/supervisors as co-authors, very little would have been gained except possibly emotionally. You will likely not even have affected a change in these people's future treatment of supervised graduate students.
So have you really
Now ... come of age
? I doubt it. This endeavor seems like the misjudgement of someone who has not come of age. You seem to want to expend extensive effort and place yourself at all kinds of risk and adversity - to right a wrong, perhaps, but in a way which will have very little effect other than personal emotional benefit.
You also use rhetoric like "so-called-supervisors" and "unreal authors", which suggests you're rather distraught about this still.
What can you do instead?
You write that:
As a PhD student I was implicitly coerced to include their names as gifts as honorary co-authors or else I would not have received any institutional support (namely residence permit and contracts).
If you can establish this coercion indeed occurs, that is a matter which is much more likely to be effectively actionable.
Consider discussing this with other (current or former) Ph.D. students; faculty members who disapprove of this practice, if you know any; the junior researchers' labor union (if your university has one); the university ombudsman, comptroller or self-inspection body if one exists; and finally, perhaps the press. But - don't focus on your individual supervisors. Instead, make this about the general problem of coercion.