The 2018 tax return is not relevant.
If you were age 19 on or before 12/31/2019, not a full time student and had gross income of $4,200 or more then you should not have been claimed as a dependent on anyone's 2019 tax return.
Both you and your father need to amend the 2019 tax returns that were filed.
He has to remove you as his dependent on his 2019 amended tax return. He will have to pay back any refund he received based on you being a dependent on his tax return.
You will need to change your dependency on your amended 2019 tax return.
An amended tax return, Form 1040X, can only be printed, signed, dated and mailed by you to the IRS, it cannot be e-filed. The IRS will take up to 4 months to process the amended tax return.
See this TurvrboTax support FAQ for amending a 2019 tax return - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...
