Better if you would reformat the OS than to delete/ uninstall everything especially in the reg editor.
To COMPLETELY do it requires going through the registry as well as manually removing the files from \Program Files x86\Common Files, \Program Files x86\, \ProgramData, etc. The registry though is the big pain as not everything is listed out as SolarWinds.
This isn't completely an answer, but it points to your answer:
Unpack the installer, then manually run each install item and do the "remove" for each one individually.