How do you record parts sold (inventory) using Periodic Inventory Adjustment?

In QBO you can do an Inventory Quantity Adjustment. Under the Plus symbol, Other, Inventory Qty Adjustment.

That's not an option.  My client is running QBO Essentials. 

You can always upgrade them to Plus, there is not much of a price difference.

If not, the JE process you are doing seems to be a good alternative.

Thank you.  What about the inventory sales- it's income (Sales-parts), correct?  

At YE my client sold about 60K worth of his inventory (sales- parts),  and has 80K Total Income.  With the monthly periodic inventory adjustments he has 48K in COGS (Beg Inv 21K (+) Purchases 75K (-) End Inv 48K.  So, 32K gross profit.  I guess this is correct, but for some reason something doesn't seem right?!  Does this all sound correct?

The formula is: Beginning inventory + Purchases - Ending inventory = Cost of goods sold. The inventory adjustment figure can be substituted into this formula, so that the replacement formula is: Purchases + Inventory decrease - Inventory increase = Cost of goods sold.

Yes. Inventory Sales is Income, you map the products or services sold to income accounts.