Yes, you can - this is done by selecting the ‘Edit' option found above the comment box at the top right of the page. By selecting this, you will be taken to the ‘Edit Conversation’ page, where you can edit your discussion title or move the discussion to a new category (categories are limited to which document categories you have access to). You can also update your subscribers of any changes by adding a helpful comment using the box provided - when you are happy with your changes, simply select the 'Next' option to continue to the subscriber management page, manage any new subscriptions you want to apply and then select 'Save' to complete the process.
You can also remove the discussion by selecting the ‘Delete Conversation’ option (again, found at the top right of the page). This will remove the discussion and all comments added from the conversation index and the event itself.