I would like to remove "Quick Create" & "Create and Edit" from all the models and all the fields. To achieve that I would like to inherit CompletionFieldMixin ( this ) and pop two values (Create  & Create and Edit ) from result returned by function get_search_result()
I tried like but

var form_common = require('web.form_common');
form_common.CompletionFieldMixin.get_search_result = function(search_val) {
    // code here
};

but above method never gets called, however I am able to call the method like
var original_get_search_result = form_common.CompletionFieldMixin.get_search_result;
But no idea how to change the restult becuase that returns the function itself.

The idea how to inherit, I got from here but it doesn't work