I'm happy to help you with deleting your transactions, but first, I have a few questions to ask:
Have you tried the app in the article mentioned by my colleague?
Are you trying to delete them individually or in one mass amount?
If deleting them individually, does the delete button work?
By answering these questions, I can determine what the issue is and gather the steps to help you fix it. In the meantime, I suggest checking out this article on voiding and deleting transactions in Online. This will show you how to delete or void transactions individually, even if they're from Quicken or PayPal.
Please let me know if this helps. I'll be on standby awaiting your response.