The order unit for material & may not be deleted

What causes this issue?

The unit of measure is used as the <DS:GLOS.order_unit>order unit</>
and may not therefore be deleted.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If you want to delete the unit of measure nevertheless, change the
order unit to another unit.

Error message extract from SAP system. Copyright SAP SE.