Removal of auditor before agm

GM can be of two types AGM ang EGM. 

Yes.. auditor can be removed in EGM. But you have to go through the long procedure if it is removal (and not resignation)

AGM and EGM both are types of general meeting of shareholders...

GM can be an AGM or an EGM....

yes the auditor can be removed before the expiry of his term(i.e next AGM)

yes, Auditor can be removed in EGM

under which sec it was mentioned

as per sec.224(7) of companies act ,auditor can be removed before expiry of term only with prior approval of central govt.(except in case of casual vacancy ) ............. 

you have to ensure that the auditor is re appointed in the AGM, if he is re appointed and compamy send intimation to the auditor and he (auditor) file form 23B with the ROC , then prior approval of the central govt is needed, otherwise you can remove him.