thanks all for the helpful advice!

I'm wondering if the failure of the Erase action is because I've loaded a preset Realtrack style. Maybe you're not allowed to delete a track. Although replacing the track with another Realtrack works just fine. I just can't clear it.

Yes, I'll look into creating my own empty style, based on the blank templates. That's probably how I want to work, since my goal is to use minimal one or two track styles.