As I am 15 years old I could't find age of travel abroad alone. What is the age of travel alone to abroad from india?
As far as I know, there isn't a law as such in India that prevents minors from travelling alone. However, each airline has their own policy on what circumstances an unaccompanied minor guest will be allowed on a flight.
Air India doesn't seem to offer too many details on its website but it does have an unaccompanied minor service, apparently. Jet Airways is more clear on what their unaccompanied minor policy is.
A child between the ages of 6 years through 12 years travelling alone or travelling with one or more guests who have not yet completed 18 years is considered an Unaccompanied Minor (UM) for international travel where the entire travel is on Jet Airways.
Note that there are further exceptions in case of connecting flights, et al that have been detailed on their website along with an explanation of the protocol they follow. There is a charge levied for this service which will have to be paid.
I've mentioned the rules for the two Indian international carriers (Kingfisher no longer operates and Indigo doesn't offer any details on what their policy is). You should be able to find a similar policy page for any other airline that you're flying with.