SAP Change Base Unit of Measure

One raw material we assigned base unit of measure as OZ, later add alternate unit of measure as ML.

Now I wanted to change the base unit to ML and alternaet to OZ. For that I deleted component from the BOM. Related PO's, Prd ord and demand are closed. Deleted the alternate unit from purchasing and plant/stock (Area were we assign the alternate unit), then try to change it giving message as Unit of measure ML used as alternate unit. (In additinal data screen still the alternate unit and conversion available)

You can do the following procedure (after deleting the material in all concerened documents):

1. Delete the uom from Unit of issue field (General Plant Data / Storage 1) in MM if you have mentioned it there.

2. Go to additional data , use delete line tab and delete the conversion factor by keeping the cursor on that line.

3. Come to main data, now change the base unit of measure to the required one.

4. Then give the alternative unit of measure, system will ask for conversion factor.

5. Then save