Is it permissible to perform tasbih after the congregational prayer and the Isha supererogatory prayer, or after shaf and witr?

The prescribed remembrance of Allah (dhikr) after prayer should be performed after the obligatory (fard) prayer, not the supererogatory (nafilah) prayer, such as the glorifications (tasbihat), Ayatul-Kursi, and the Mu'awwidhat (Surahs Al-Falaq and An-Nas). These should not be delayed except for a valid excuse. Therefore, pray the obligatory prayer, then perform the prescribed remembrance, and then pray the supererogatory prayer. If you wish to remember Allah and recite the Quran after the supererogatory prayer, that is good.