Yes, you are able to claim your unused tuition amounts from 2014 and 2015.  You will need to file income tax returns for both 2014 and 2015.  Once they are assessed by the Canada Revenue Agency, you can file adjustment requests to your 2016 and 2017 income tax returns to claim the tuition.

Please use this link to access prior year returns, https://turbotax.intuit.ca/tax-software/prior-year-taxes.jsp.  You can use TurboTax to prepare your 2014 and 2015 income tax returns but you will need to print them out and mail them in because NETFILE is only available for 2016, 2017 and 2018 income tax returns.  

Please see the following FAQ for information on how to file an adjustment request:

https://turbotax.community.intuit.ca/replies/2647992