Clearing Product Data (Advanced purchase note)

I made a huge mistake. I thought the purchase note was for me when I did purchase orders. I was wrong.
I have thousands of products and I’m slowly going through each one.

Is there a way to clear all of them at once? Or am I screwed and have to go through them one by one? Because I didn’t make a note on every one. Just a few. I don’t remember the few that I did.

The field is under product data
Advanced
Purchase Note

Please tell me there’s an easier way than me going through them one by one.