If you have not submitted your return:

1. Go to the Menu on the left side of the screen and Click My Info 
    

    

    Your name's personal information
2. Make the correction and click Continue

If you have already submitted your return:

You can request to Canada Revenue Agency (CRA) a change to your tax return by amending the amount entered on specific line(s) of your return.

For more information, visit How to change a return 

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