Hello SYURI,
I am assuming you want to replace the media for a particular token. Can you share if these steps work for you:
On the Edit tab select the Edit button in the Media section.
Then remove the existing image by either clicking the garbage icon
You should then be able to upload a new token image.
Also additionally, it’s possible this was concurrent with this bug that was fixed here: Unable to publish updates to a new token - #12 by johnny
Let me know if either of these resolves your issue,
Nikki