We are unable to make any non-system-level modifications to customer apps and/or databases for Security and Legal reasons.
To make changes yourself, you can log in to your account and upgrade your free dynos using the instructions here.
If you would like to change the ownership of the app so you can have someone make changes on your behalf we have more information on how ownership of an app can be changed here.
See our blog post and the Removal of Heroku Free Product Plans FAQ for more info related to the ending of free plans.