When withdrawal fails, quash can be resorted to. Not by the Informant, however. State rarely goes in for quash. Accused should. Quash is requested when a case is frivolous or vexatious. In such a matter, applying for Discharge by the Accused is an easy and inexpensive remedy. The Informant will, in this case, help the Accused.
If the Assistant Public Prosecutor withdraws and if the trial court gives its nod, the permission of either the Sessions Court or the High Court is unnecessary. High Court can, of course, revoke the case. Only in the rarest of rare cases.