Hi Arun,
Please not that LoadRunner 9.x is not supported.
Generally when you want to downgrade you will need to uninstall the higher version of the product and install the previous one. However you will still need licenses in order to be able to run load tests in Controller.
If you have licenses for LoadRunner 9.x, they could be reissued for LoadRunner 11.5x by opening a licensing case with support.
Instuctions are available under Logging a Support Case in the following document:
http://support.openview.hp.com/pdf/HP_Software_Customer_Support_Handbook.pdf
Kind regards,