Clearing the Recent Searches Dropdown Menu in Calibre's E-book Viewer

I'm using the E-Book Viewer software that comes with Calibre (osx) in order to search the isbn tags of my epub files, and I really liked having "isbn" be the only result I got from the dropdown menu of my recent searches because I could just click the menu and quickly click "isbn" from there.

Anyway, I accidentally added another word to the searches, so now when I click the dropdown menu, it shows "isbn" and "(other search)" instead of just "isbn".

Is there any way to clear the recent searches so I can get rid of "(other search)"?