When you Uninstall SQl server some of the traces will be left behind one of them are Reporting serivces catalogs in order to fix this issue follow the screen shots below
Next to go to the Sql server root directory, by default
C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\DATA
z
Files to be deleted
- ReportServer.mdf
- ReportServer_log.LDF
- ReportServerTempDB.mdf
- ReportServerTempDB_log.LDF.