I keep customizing the toolbar and adding the delete button, and it randomly goes missing.
If I put it there, close composer and reopen, it stays. I just put it back, created new package and closed/reopened and it stayed.
I'm having this issue on multiple machines now, I tried Composer 8.64 and 8.7 (so a brand new copy). I am going to try to better track when it goes missing... maybe I'm just going crazy. It's that time of year.