1) Uninstall the Simplify3D software
2) Delete the folder and the remaining files in “program filesSimplify3D-x.x.x”
3) Delete the folder and the remaining files in “C:UsersxxxxxxAppDataLocalSimplify3D”
4) Delete the entire registry key “ComputerHKEY_CURRENT_USERSOFTWARESimplify3D”
5) Restart the computer
6) Reinstall Simplify3D if needed