Fixes incorrect processing of deleting metadata

When a non-admin tries to delete metadata from a marked image,
they are correctly getting an error message, however they are
also getting a success message when they shouldn't. This code
fixes the incorrect success message.

Closes-Bug: #1308519
Change-Id: I909551365b4a92675d26c1da754e586685a4aa32
Merge "Fixes incorrect processing of deleting metadata"