No, please don't invalidate existing answers by editing
The bounty reason you named is supposed to be used if for example new research came up or on some other sites on the network if the programming language in question is updated. Things where it's outside of the control of the participants. See for example: Invalidate an answer when starting a bounty
Invalidating answers by editing your question is not okay. You would invalidate their hard work and it makes it a lot harder to keep track of which answers are good and which are bad. See for example: On editing questions and invalidating answers
The best thing to do is to post a new question and link to the old, stating what exactly you changed and why that would invalidate the existing answers to the old question. That way you also show why the new question is not a duplicate - if the edit would invalidate existing answers then the answers can't be useful to the new question and it can therefore not be a duplicate.
Be sure to make this obvious. Make it bold. At the start. With a horizontal line before the stuff you basically copy from the old question. It doesn't matter how you do it exactly, but make sure that everyone sees that you are asking a similar question, but with definitely different constraints that make the old question not useful anymore for finding an answer to the current question.