Report Server: how to edit/delete user rights via relational database

Hi all,

we have the following problem on our report server: it exists a report where different users have only the security role "Browser" on it. No one can change or delete this report, because the rights of the administrators were removed by mistake.

Is it possible to change the RoleID via relational database of the report server?

We saw the table PolicyUserRole and SecData on the database, but we don't know where we should modify it and how it works?

An additional question: How can we avoid such a scenario in the future? Administrators should always have the rights to access and modify a report, even if the rights are deleted.

We hope that someone can help us.

Thank you!