How to clear the difference in the Storage type 999 with Storage unit

The warehouse structure

Storage location A is IM level.

Storage location B is WM level and HU managed.

Step1:

Initial Material X is 30 pc.

Stock Transfer 10 pc Material X from storage location B to Storage location A

this will generate a Delivery.

Step2: Create TO reference the DN

Step3: Confirm the TO ,

the Actual Pick qty is 15. more then the required qty.

So there is TO difference. -5 into the storage type 999.

Step4: PGI of the Delivery

After PGI.

the stock in WM will show like

Material X

In storage bin A001 Is 20PC with HU number 1000

in storage type 999 is -5PC with HU number 1002.

Question is: How to clear the difference of the storage type 999.

It's can no use LT01. because of the difference HU,