How do I unselect a LOWINC (Low Income Housing) credit on a Massachusetts state income tax return?

I accidentally selected a LOWINC credit on my Massachusetts state income tax return because I live in low-income housing, but when it asked for a certificate number I realized it wasn't something I qualify for. Now I can't file because it wants a certificate number I don't have, but it won't let me edit the selection. It just keeps circling back to the certificate number. I tried all zeroes and it didn't work. I spent an hour in the phone with customer service and they couldn't help me change it. They told me to file as is so I continued, paid, and after I paid was told I couldn't file until this error was fixed. I can't clear and start over because I already paid and I didn't know that was an option until after I paid. I don't know why customer service didn't suggest that. So now I'm stuck.

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