We are looking into this and will get back to you.
If you are wanting to completely clear out the database and start with a fresh database try deleting your NetPerfMon-Elements.mdb and/or NetPerfMon-Elements.cfg files and then doing a repair on the Toolset installation to replace your database file.
Depending upon what version of Toolset you have you can find those files in the following locations:
Toolset installation folder. Default location is C:\Program Files\SolarWinds\Toolset
All Users App Data. Default is <All Users Profile>\Application Data\SolarWinds