You shouldn't need to override here, doing so would make you ineligible for NetFile.
To make the election or enter the details of a previous election to stop paying CPP on your Self-Employed earnings using TurboTax Online or in the EasyStep view, go to Income > T-Slips > T4A(P) Canada Pension Plan Benefits.
On the T4A(P) - Summary screen, you can enter your information about previous elections or choose to stop contributing to CPP on your self-employment earnings. In your case, you need to ensure you have said "NO" to the question - "Did you elect to stop contributing to CPP on your self-employment earnings in a year prior to 2018?"
Also, make sure the CPP Exempt button is still set to NO on your T4.