I finally decided I was done being sad looking at the name of my covid-casualty former band in my projects list. I went into the web app, into that project, batch-added every song to my new band project, and then went to Account > Projects to deactivate it.
I tried from the list/batch direction but for some reason it wouldn't show as deactivated. I drilled into the project detail and found the "Active" box checked and greyed out, so I physically couldn't uncheck it. None of my other projects were this way.
Then I realized I was IN that project. I changed to a different project and suddenly my old band's project WAS able to be deactivated. Makes sense--what would you do in the UI if you were suddenly in the context of a deactivated project? But I had a very confusing moment until I sorted that out.
Some sort of messaging to that effect would be easy and helpful, in this (admittedly, edge) case.
I'm sorry to hear about your band casualty.
I think this is mainly a problem when batch-updating, because you realized what was happening after seeing the disabled checkbox on the project edit page. I'll look into adding that message to the batch update function. (BTW the same issue would happen if you tried to disable your own user.)
I just added error messages if you try to deactivate your current project or user.