DATE column doesn't like empty string or null value

Hi Group:

I used COPY to import a bunch of data into my PG database.  The db has
one table so far, and the table has a column using DATE with a
datestyle of US,ISO.

To get all the data to copy correctly, I created a meaningless date
entry of 01/01/2001 and inserted this into every row in the database.

I would like to delete these bogus date entries and leave the date
column blank until proper dates can be filled in.

What command can I use to remove all the 01/01/2001 entries in every row
and leave it blank.

Thank you for your time and patience.

Mike