By delete do you mean unsubscribe? If so when you get the email notification you can unsubscribe there to that thread or all threads. Of that's NOT what you meant then I have wasted my time typing and your time by reading. For that I apologize.
I don't have an issue scrolling through threads I've posted in and most if the time when I get an email notification I just open it up in safari to respond. BUT... I do understand what your saying and it wouldn't be a bad idea to have the threads bumped up to the top in bold instead of going through 500+ pages.
But... That's the app and the powers to be, still love the forum and the app.
"When creating an aqua scape, strive for the beauty of imperfection, as its art and there is no wrong or right, it's left open for interpretation" James Findley