How to clear the large amount of dead stock from the store?

it depends on the nature of your stock , based on the cost and the nature of the stock you can :

1- discount it 

2- include it in a promotional set of items 

3- make it a gift  as marketing method 

4- donate to reduce your taxes

5- return it to your supplier if you can or replace it 

6- sell it to your company staff 

7- sell it in different market local or international

8-waste it or use as spare parts 

and if  you have  powerful stock control software implemented for your business to alarm, indicate and guide you how to manage such stock and it will revert your work to an automated one.