Which version of NPM? Did you delete the reports you don't need from C:\Program Files (x86)\SolarWinds\Orion\Reports? AFAIK, a Config Wizard doesn't restore the out of the box report list if already deleted from the above folder.
When the web reporter was introduced, any legacy reports created would be automatically copied to the database. So, if you deleted them only from the web console but were still left behind the Reports folder, a Config Wizard will re-copy them to the database and hence appear in the web console. That is what you might be experiencing