I've screwed up and put some incorrect data in my custom2 field on uploading my new users for the coming school year.
I'd like to re-upload, leaving custom2 blank so it deletes that incorrect information, but so far haven't found the field content magic to make that happen. A blank space or more than one in the .csv throws an error, quotes reproduce as quotes, a quote with a blank space reproduces as a quote with a blank space and throws an error. The only success I've had is to put a . in the field, and it uploads that character, replacing the erroneous data.
Is there any way to clear the data in custom2 using batch upload?