2018 excess Roth contribution after 12/31 deadline

My husband and I contributed to a Roth IRA in 2018 and 2019. We realized on 1/31/2020 that we shouldn’t have contributed to either. We understand the 2019 can be converted to a regular IRA and then back door converted back to a Roth. However, what do we do to fix the 2018? Everything I read says we should have fixed by 10/15/2019. What should financial institution do for the 2018 funds? What should we do from a tax standpoint? Please help with the most cost effective solution! I understand that we will owe a 6% penalty for 2 years, is that right? Also, are we gonna be hit with 10% early withdrawal? We are under 40years old.  Trying to determine best way to try to keep all in a retirement fund of some sort if possible!