Can you follow these steps:
Open Software & Updates
Move to the "Other Software" tab. Scroll down to the Microsoft Edge Repository and click on it to select it. Then click the "Remove" button.
Close Software & Updates.
It will ask to refresh - it is fine to refresh the cache.
If you have replaced Edge Browser and no longer use it, you can remove Edge Browser and are done.
If you still use and prefer Microsoft Edge Browser, proceed below:
Open terminal and run this to get the Signed Key you need
I thought the no_pubkey error for edge was fixed in a recent release.
Well...I was wrong, perhaps.
This tutorial by @FrenchPress can solve that problem.