I made an error. How can I fix it.
This TurboTax FAQ tells you how to make changes to a tax return that has already been filed:
https://turbotax.community.intuit.ca/turbotax-support/en-ca/help-article/accounting-bookkeeping/filed-tax-return-still-make-changes/L992Trv7f_CA_en_CA?uid=lvjtjjtv