Cognos has the inbuilt command line to install the software silent,. like .iss file it has .ats file which will be present in the source but that is 0kb so install the source and search for the .ats file we will get .ats file.
The commandline to install is
<Path of the exe> -s <path of the .ats file>
Same way we need to uninstall the software with the help of .ini file and uninst.exe.The uninst.ini will be present in the source file.
so the command line to uninstall is
<path of uninst.exe> -u <path of uninst.ini> -s