Hi Eric. I believe those New Task / New Issues buttons automatically appear whenever the person viewing the dashboard has rights to take those actions -- in other words, they are security driven. So, to remove them (e.g. if you are trying to give a read-only view of a dashboard for a wider audience), perhaps you could set the Run As credentials on each report to a (special) user account that has no such permissions (e.g. reject its rights to take such actions), and in so doing, suppress the logic that would otherwise present the buttons.
Regards,
Doug