That thing about the "suggestions" is the Discourse platform's attempt to prevent duplicate topics (or topics with nearly identical content). It is a suggestion that perhaps what you're posting has already been discussed. Don't worry about it, You may have noticed we still have lots of topics on the same subject.
I'm not a frequent user of the mobile site, but if you want to delete something you posted here, click on the 3 little dots under the comment. you'll then see the trash can icon.
if you want to edit something you've posted, and not delete it entirely, click on the little pencil icon.
you can also flag comments, clicking on the flag symbol - this immediately sends a notification to the admin team to take a look - we want to help you have a helpful experience here.