In order to rename computer that runs a SQL 2012 report server, do the following:

1. Open RSReportServer.config in a text editor and modify the UrlRoot setting to reflect the new server name. The UrlRoot setting is used by delivery extensions to compose the URL used to access items stored on the report server. Changing the report server URL address requires that you update the UrlRoot setting so that subscriptions continue to deliver reports as expected.
2. In the same file, if it is set, modify the ReportServerUrl setting to reflect the new server name. Note that this setting is not used in every installation. If it is empty, do nothing.