How can I permanently delete emails and delete from recovery

You can't.  Emails in the recovery folder stay in it until they have been there for 30 days.  After that they will drop out and can no longer be recovered.  There is no way for you to change the default behavior.

Who told you they can't be recovered? It's not true. I had my Xfinity email hacked 12/2020. I have good pc protection and kept nothing in the email they could use. BUT, here's the thing - the hacker called up all my old emails from at least 6 months prior. I know because my trash (emptied the day before) was full of old emails - some from June 2020. If it's not recoverable, how did that happen?

If you go through webmail to settings -> mail under "behavior" there is checkbox to "permanently remove deleted emails". I believe that is what you are looking for.

I have this question as well. There are items in my recoverable items bin from Dec 2020. That's way more than thirty days. I understand it's from the time one deletes them from the folder, i.e. I didn't delete an item until yesterday from March--but I'm pretty good about clearing out my email boxes.

Also I see that there are items I haven't yet deleted (from today for instance) that are showing up in the recoverable items box. There are items I deleted yesterday that are duplicated in the recoverable bin.

Why is that?

I want to be able to delete permanently items I don't want anymore, including from recoverable items. Sure, it's a great tool when emails have been accidentally deleted, but something isn't working correctly. Or it is and I'm not understanding why it's set up that way.