Welcome to the Community, Hina. When you record a sales transaction in QBO, the quantity of the item sold will automatically reduce your available stock in the inventory.
On the other hand, purchasing items will increase your inventory quantity. If you're asking whether to proceed with posting the sale, let's ensure that the number of items reflects what is available or what should be in stock.
While the program allows selling items beyond inventory levels, it could result to negative quantities. If you mean something else, I encourage posting more details below. This will allow me to better capture the entire situation and offer you a more targeted solution.
In case you want to edit an item's quantity without recording a purchase or sale, please refer to this article: Adjust inventory quantity on hand in QBO.
I'll be around if you need further assistance with managing your inventory items. We're here to help.