How do I clear the Work in Process balances after all the product completions?

The WIP balances are cleared after the work order is closed. If you're using the standard cost method, the balances in WIP will be cleared by creating different variances. If you're using actual, average, or periodic average cost method, product cost adjustments will be created.

In the case of periodic average cost, if the product completion and word order close are in different periods, then the adjustments will be created to clear the balances. If the product completion and word order close are in the same period, the completion costs are recalculated.