Hey, thanks for the detailed feature request. Good news, this is already done. In Edit Icon, there will be a “No icon” option that resets the chat back to the default state with no icon. So you’ll be able to remove the icon without renaming or archiving the chat.
It’s not in your version 3.17.21 yet, so that’s why you don’t see the option. It’ll ship in one of the next releases, so keep an eye on updates.
Also, you have another thread with the same request: "Edit Icon" cannot be deleted after adding an icon to a session. You can keep this one to avoid duplicates. Let me know if anything doesn’t work as expected after you update.