Cannot remove work account from Authenticator in old Android phone

Last year i upgraded from Samsung Galaxy S8 to Note 10+ and transferred all work operations with my Microsoft 365 accounts over including obviously Microsoft Authenticator. Everything was fine and i retired the old phone, deleting the device off AAD.

Now we're testing MAM App protection policy for Android and i brought back theold Galaxy S8 for selective wipe tests. I subsequently noticed its Authenticator has an inert entry for my Microsoft 365 account- cannot interact and delete it. I thought it was deleted previously. My other personal Microsoft accounts interact properly.

Is that a natural consequence from the MAM tests? How can i completely remove it from the old phone?