When you have an FBA removal order, your FBA inventory will get readjusted automatically. However, you will still need to manually adjust your local inventory to reflect the returned inventory.
To add back inventory to your local stock, simply adjust the product stock to the new total.
This can be done by navigating to Inventory>Product in Planyard, then clicking on "Details" for the respective product. After that, proceed to the "Stock" tab and edit the stock quantity to reflect the new quantity. This step will ensure your local stock levels are up-to-date.