So far, I solved the issue about deleting unwanted contacts myself. It was solved the hard way. I ejected the MicroSD and stored all tracks, routes, waypoints to BaseCamp. Then I performed a full reset of the GPSMAP 67i.
The Android phone Explore and Messenger apps that are developed as accompanying apps for the GPSMAP 67i both reported my unwanted contacts as gone / not showing. explore.garmin.com/Contacts reported the contacts as gone. The 67i itself reported the unwanted contacts as existing in some kind of read only mode.
Full reset/factory settings was then performed. The 67i was connected to my PC with Garmin Express afterwards. The standard maps was enabled and the 67i appeared as when it was brand new out of the box.
When the 67i was restarted and paired with my Android phone again,
I didn't allow the Explore or Messenger apps to connect to my phone contacts and I haven't allowed the apps to look for other inReach/Explore contacts in my phone contacts. So far, I don't have any unwanted contacts now and I haven't tried to delete any contacts off the 67i yet. My few favourite and reqiuired contacts to receive and communicate inReach messages have been enabled on the 67i.
I haven't addressed this issue to Garmin Support yet, but if the scenario recreates itself I will.
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