In general:

Before Departure:    Can be done on request of the insured via mail  

After Departure:      Can be done on request of the insured via mail but Original Passport  verification is a must to check the valid reason.

 1. Insured has to pay cancellation charges which vary from company to company towards Administrative Expenses.

2. Request for cancellation of policy should be received prior to expiry of the original Policy.

Imp: Please refer Cancellation and refund policy of each insurance company  given against their respective travel insurance plans on our website. Cancellation charges too are given .