Remove a Single Note From an Existing Diagram

I found a diagram I like with major scales and major arpeggios. I would like to use it as a base for a diagram of mixolydian scales, so I want to remove the major 7th. However, I can’t for the life of me find a way to remove a single note. I also can’t figure out how to remove all the notes and use the scale generator for my purposes. How do I do this?