You could delete it in Content Manager, then delete missing assets in the route. That is what I do if I cannot find something or it is placed on the route a lot. You can re download it then, once the route is saved.
I have 8 packaged assets on my route and 11 on the session. I have not downloaded any routes since I started this. Why do I have these. This PACKAGED shit has me looking to not share the route and session.
Man, a lot of old people here, LOL. I am 84 and have been on trainz since 2006. I have always been into model trains since I was a kid. But when I got married, I had no room for my models. So, I got into this to help my addiction.