What does the community want to do?
There's honestly not much the community can do here, other than try to perhaps help you understand why your previous question(s) were poorly received so that you can improve your questions in the future.
As the help says, deleting the question won't help recover your reputation. The damage from asking a question that was poorly received can't be undone with a deletion.
And deleting questions with answers has a different, but similar, penalty system.
If the question could be improved to encourage upvotes (or encourage some voters to reverse their downvotes), then that would be the first option. However, I'm really not sure that's likely in this case.
I assume that, if you are receiving the "Some of your past questions have not been well-received" message, then it isn't just this one. It sounds like there are some questions you've asked in the past that have been downvoted as well. I assume those have already been deleted - Perhaps by you, but more likely by the Roomba bot that clears certain downvoted questions after a span of time. So I can't offer suggestions on past questions, really.
Looking at this particular one, however, I don't think it can be improved to gain upvotes. While it's impossible to truly know the reasons that three individuals downvoted your question, I can make some guesses.
As the How do I ask a good question? page says:
Search, and research
Have you thoroughly searched for an answer before asking your question? Sharing your research helps everyone. Tell us what you found and why it didn’t meet your needs. This demonstrates that you’ve taken the time to try to help yourself, it saves us from reiterating obvious answers, and above all, it helps you get a more specific and relevant answer!
There's no indication in your question that you searched for that particular error, and there's no list of what you tried to do to solve it on your own before posting.
Usually, my first step would be to look for common words in the error, remove any "specifics" like filenames or processes, and search on that. For instance, from your error:
W: http://repo.mysql.com/apt/ubuntu/dists/bionic/InRelease: Key is stored in legacy trusted.gpg keyring (/etc/apt/trusted.gpg), see the DEPRECATION section in apt-key(8) for details.
I took the search terms:
- Key is stored in legacy
trusted.gpg since that's a specific filename that could vary between users' systems. So I search for:
Key is stored in legacy keyring DEPRECATION
In this case, however, even the specifics ...
Key is stored in legacy trusted.gpg keyring
... would have been fine.
Either result would have provided some things to try.
Whether they worked for you or not, when you write your question:
- Include the links to other questions (or sometimes even websites) that you found in your search(es)
- Include what you tried from them
- Include any messages or errors you received or why they didn't work
Often, you'll find the answer to your question when writing a good question.
Again, taking an educated guess here, that's why the question received downvotes -- A lack of research (at least as shown in the question) and helping us understand what you had already tried.
As for the questions I can't see, if there are any that you think might be salvageable, perhaps I'm wrong on this, but I would recommend trying to do so. You can then bring the question here to Meta and ask those with 10k rep or higher (who can see deleted questions) to review your improvements and see if it might be worth reopening and then upvoting to recover reputation.
But the best advice I can give you going forward would simply be to make sure you are following the guidelines in How do I ask a good question?.
Some additional reading material from the Stack Overflow page on the same topic -- Writing the perfect question