Mumbai DCR Regulation 51(i) states: Apart from residential use, Customary Home Occupation shall be permitted in buildings, premises or plots in a purely residential zone.
"Home occupation" is defined as customary home occupation other than conduct of eating or drinking place offering services to the general public customarily carried out by a member of the family residing on the premises without employing hired labour and for which there is no display to indicate from the exterior of the building. In other words, you or a family member must reside in the flat, must not have employed labour for the purpose of classes and there must be no display in the exterior of the building advertising your classes.
Regulations seem to Permit but You may have to read the govering by-laws of your housing society to understand if you would require permission for conducting classes.
This question has been answered here. https://www.questate.in/question/how-many-students-can-be-taught-at-a-time-in-my-residential/
