How to uncheck a checkbox programmatically? How can I uncheck a checkbox programmatically in Drupal 8.
I need this in an ajax call, when an option is selected, a checkbox must be unchecked
After a lot of trial and error, I found out:

Imagine a checkbox with name 'Coffee' has one option: ['Y' => 'I want an espresso'].

To uncheck this selection, enter:
$form['Coffee']['Y'][#checked]=false