Here’s a template letter of how to do so under GDPR. You must request your data or the deletion of you data using the correct legal framework (quoting the correct legislation) and these templates make this easy. Plus they cover more types of data than just your posts and comments.
https://www.datarequests.org/sample-letters/
You could consider making a data request first and after they respond, make a deletion request.
Template letter to request your data or delete your data under GDPR here if you need it: https://www.datarequests.org/sample-letters/
This will go to a vote in the Dail tomorrow. If you’re in Ireland, would you consider emailing or calling your TDs today?
As Ireland is such a small country, it only takes a few people to call or email for them to take note.
Find your TDs listed here (edited link): https://www.oireachtas.ie/en/members/tds/