When you hover the mouse over the macOS-App "1.0 Bereit zum Verkauf", do you see a red "-" (delete) button?
From https://help.apple.com/app-store-connect/en.lproj/static.html
You can delete a platform if a build has never been uploaded for the platform you wish to delete.
Additionally, at least one existing platform version needs to be in an editable app status.
See App statuses.
If the criteria is met, hover over the platform you wish to delete and click the delete button (–) that appears to the right of the platform.
This is slightly confusing, but it works...
There must be an editable version for another platform, for the delete button to show up.
Like this (1.3.11 for iOS is editable, so I can delete the macOS version):
Then the macOS version can be deleted.
Topic:
App Store Distribution & Marketing
SubTopic:
App Store Connect
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