Quit job of 3rd party payroll - how do I approach? What should be the notice period and all?

Recently I joined a MNC via third-party payroll. I am a current employee of the payroll company itself. So, HR didn't issue any offer letter from MNC neither I signed any contract. All I got a salary hike letter mentioning I am deputed in some MNC project. And signed just a Compliance form to use their resources as laptop provided. If I now want to quit how do I approach? What should be the notice period and all?

I assume the compliance form was to comply with the company's regulation on use of assets and so that mistakes or violations by you are not the liability of the company. It does not make you an employee of the company.

If you wish to leave, send your resignation to your actual employer (the third party company who give you the job).
However, if you have good relations within the company you are deployed in, it would be a good idea to verbally inform your reporting officer of your decision to resign, as a mater of cutesy