You can make fields blank in Oracle by using the [BLANK] functionality in Item Wizard.
If you wish to override a field in Oracle with a null, you must enter ‘[BLANK]’ in the cell before you upload. If the cell is left blank in the worksheet the API will not interpret this as a command to remove the value from the database record and the value will persist.
Note - You cannot use this functionality on the following columns: Inventory Planning Method, Make or Buy, Safety Stock Method or mandatory Category Set values.
You should not use this functionality on any mandatory field values.
