You can get refund from IRCTC for cancelled tickets which you have booked.Here IRCTC clearly separated each cancellation rules as it could be different types.Below I am putting these cancellation ticket categories :
Confirmed tickets : It indicates that your ticket reservation is confirmed and you are ready for the journey.
Partially confirmed : It is also confirmed but not fully.Most of the time partial confirmed tickets becomes confirmed very soon.
RAC/Waitlist – RAC indicates (Reserve Against Cancellation) therefore if someone cancel their tickets your reservation may have confirmed status.
Above reservation tickets are mostly considered to be cancelled and each cancellation charge is different.
You can cancel your ticket from IRCTC reservation counter,if its E-ticket you can do it online.