Problem: How to remove a value from a field using update in bulk import? For example, user might want to change storage location to virtual of multiple specimen in one go.
Solution:
During bulk import, under the corresponding column in the CSV file keep the value as '##set_to_blank##'. This will remove the value stored in that field and update it to blank or no value. This is allowed only for optional fields.
This will work for custom form fields too.