This thread is resolved. Here is a description of the problem and solution.
Problem:
The client is unable to disconnect a translated page from the original English page after mistakenly connecting it to the wrong translation.
Solution:
It was a known issue that is solved in WPML v4.6.8 as mentioned here: https://wpml.org/errata/wpml-4-6-7-issue-with-disconnecting-translations/
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