Yes it's possible to delete any post you have posted on social media but the post will not be deleted for the managers and the social media platform/team. You may not see it and people but the managers and people behind the app will still have this.
The last one. The only scenario where you wouldn't put a comma in the first quote is if it's a completed remark that uses particular punctuation such as a quotation or exclamation mark, but never a period. Hope this helped.
