Update Sales Product Type attribute from any value to blank

I have some items with a value for Sales Product Type attribute and I would need to put it in blank. I have performed the following task but the update was not performed.

• Try to update manually in Oracle Cloud the attribute. When I click to display all the possible option, I can select any value but not to leave the attribute blank.
• Update the attribute by using the FBDI for Items adding #NULL for this attribute.

Additionally, I would like to clarify that I have full access to PIM and I have the ability to modifiy any Item attribute.