You can certainly cancel Bus tickets that are booked using Niki. You can now do it from the app itself. Go to My Orders under the Menu section and tap on the Bus order listed. Tap on Cancel Ticket button on the screen. This will cancel the ticket. Once this is done, you just have to write to support to confirm the cancellation and process the refund.
P.S.: Please note that cancellation charges will be applicable as per the travels’ policy and the balance will be processed as refund back to your account. We will also send you an email confirmation once the refund is processed. Any cashback earned as part of this bus ticket booking also will be reversed on cancellation of the ticket