We do not currently know of any antonyms for adhan.
The noun adhan is defined as:
The call to prayer, which originally consisted of simply four takbirs followed by the statement لَا إِلٰهَ إِلَّا ٱلله (lā ʾilāha ʾillā llāh) (أَشْهَدُ أَنْ) ((ʾašhadu ʾan)).