I appreciate you for following the steps provided by my colleague above. To effectively reduce your stock level, please input the prepayment as a negative value, evinna.  

Adding a negative value to your Other Current Asset (OCA) account in the Bill section will adjust the balance, accurately reflecting the amount owed after the prepayment and ensuring that your financial records are accurate. To correct it, please follow the steps below:

1. Go to the + New.
2. Select Bills.
3. Add the necessary details.
4. On the Category details, add the Prepaid Inventory to the Category column.
5. Once done, add the negative value to the Amount column.
6. Then, enter your items.
7. After that, click Save and Close.

Once done, we'll have to pay the bill balance. Please follow the steps to do so.

1. Go to the + New.
2. Select Pay Bills 
3. Choose the correct Payment account and ensure to set the right Payment date.
4. Select the bill you created.
5. Once done, click Save and close.

I'm including this article to show you all your payments made to a supplier: Expenses by Supplier Summary report.

Please feel free to post in this forum if you need more help with this issue.