Hi Camilo,
Thank you for your question.
Currently in the AdWords API, once you create a product partition as a BiddableAdGroupCriterion or a NegativeAdGroupCriterion, you should no longer be able to edit its nodes (subdivision or a unit) to become the opposite of what it was originally.
In short, you would need to remove it first and create a new tree entirely to either target (BiddableAdGroupCriterion) or exclude (NegativeAdGroupCriterion). You may refer to this section of our shopping campaigns guide for more information regarding partitioning. I hope this has been helpful.
Best regards,
Peter
Google Ads API Team