There is no issue related to this API.

As input, pass the ID from the SRD_CUSTOMER_EQUIPMENT_STOCK table in the SOAP request.
To retrieve the data, use the following query:

select * from SRD_CUSTOMER_EQUIPMENT_STOCK;

After executing the API, check the SRD platform report (/reporting/customer-equipment-stock).
The status of the concerned Customer Equipment Stock will be updated to "UNAVAILABLE".

Please provide a sample in Omantel platforms 179 and 84 and to be demoed in SRD UI

How to verify:

Step 1 : Go to Inventory -> Customer Equipment Stock, pick any row and note its Item Code (exemple CODE111)

Step 2 : The ID is not shown in the UI so retrieve it from DB using the Item Code:
SELECT ID
FROM SRD_CUSTOMER_EQUIPMENT_STOCK
WHERE ITEM_CODE = 'CODE111';

Step 3 : Call the API with the retrieved ID:

<ser:removeCustomerEquipmentStocks>
<arg0>THE_ID</arg0>
</ser:removeCustomerEquipmentStocks>

Step 4 : Refresh tha page Customer Equipment Stock, now you should see the status of this row = UNAVAILABLE.