I am owner of 3rd floor.2nd floor owner is using front space of staircase.he put shoe reck and dustb

The regulations of the housing society or apartment association typically govern how common areas, such as staircases, are used in apartment buildings. The state's Cooperative Societies Act and Apartment Ownership Act are the foundation for these regulations. Common spaces, like stairwells, are for everyone's use and cannot be occupied by one person for personal belongings like dustbins or shoe racks. It's probably against the rules if the second-floor owner uses the stairwell area for private storage. Every community has rules that, to allow everyone to use them freely and safely, typically forbid citizens from putting personal belongings in common areas.  Do check with the society by-laws and raise a complaint to the concerned authority of society if needed.

The stair case is a common area and nobody can have any exclsive rights over such common places.

You can instruct him to remove the obstacles on the staircase which is causing you disturbance to use the stair case, if he is not listening then you can make a complaint to the association, if the asociation do not take any action then you may initiate appropriate legal action as per the circumstance

Get the shoe rack and other items removed from staircase and other common area(s) which are meant for use of all residents and not the occupant of floor.

Approach MC / Office bearers of management / RWA of apartment