Thanks so much for the clarification!
I figured that Discourse worked like that but its nice to have a concrete answer!
How do you do this? I have a theme and am uploading assets in a /assets/images folder within my theme. The assets are then uploaded to discourse and I can view them if I go to Admin → customize → myTheme and look under the uploads section.
Pressing the ‘x’ doesnt delete the asset immediately (I think)? its flagged for deletion and deleted after some amount of time?
I just want to get the process right so that I know how to deal with this in the future 
Thanks so much for you knowledge so far! Its been beyond helpful!