If you did not indicate you can be claimed by someone else on your tax return and have already filed, then your parents' return will be rejected when they e-file their return claiming you as a dependent.
To correct this, you'll need to amend your return and indicate that you can be claimed by someone else in the Personal Info section. The IRS will take 12 to 16 weeks to process your amended return and your parents will not be able to e-file.
I recommend that your parents file their return by mail. By the time that the IRS processes their paper return, your amended return would have processed and everything would match.
To amend your return, please read this TurboTax FAQ:
https://ttlc.intuit.com/replies/3288565
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