It can be done within 15 days from the date of receipt of policy document i.e. Free look period. (mymoneysage.in)
Free look period: You can cancel the policy within 15 days of receipt of the policy documents if you are not satisfied with its coverage, features or terms and conditions. (policybazaar.com)
You have 15 days free look period (15 days from the date of receipt of policy bond / document). (relakhs.com)