Locate your Cities2.exe, to do so ..

• Rightclick on Cities Skylines II in your Steam library
  
• Choose properties, installed files, browse
  
• (New window pops up)

Copy the game path

• Leftclick into address bar
  
• Copy the content with CTRL+C

Open properties again

• Rightclick on Cities Skylines II in your Steam library
  
• Choose properties, general
  
• Click into launch options
  
• add "
  
• press CTRL+V
  
• add \Cities2.exe" %command%

Don't forget to uninstall Paradox Launcher, as it runs in background.
Use Windows Apps - Uninstall for it. No further cleanup needed.

Paradox Launcher violates personal data protection rights, according to the European law.
This software installs without your agreement, scans your PC, captures every available telemetrics. Paradox stated not selling this data to third party companies, but everyone knows this is BS.

• This guide works for almost all Paradox / Steam games.
  
• Display fps: "Steam settings", "InGame", "In-Game FPS counter"
  
• You can use Paradox Mods even if Paradox Launcher is deactivated