Here's the COMPLETE answer: To avoid the 6% penalty on the amount contributed (any amount contributed is considered "excess" if you didn't have any net income) take a distribution of the full amount for that year + gains (interest, dividends, appreciation, etc.) if any. The gains will then be subject to the 10% penalty if you're under 59-1/2 (or whatever other exception may apply in your case. None apply in my case, and I did not invest any of my 2018 contributions because they were too small - I just earned simple interest.
So I called my brokerage and completed a form to transfer the 2018 cash contributions + the interest to my primary brokerage account.
It may be possible to recharacterize all the 2018 contributions as 2019 contributions, but I'm not so sure that would work - if you had a lot of capital gains or dividends, then that might be something you'd want to try.
In TurboTax, I indicated that I took the distribution so that TurboTax can properly attach a statement explaining the reason for the early distribution (at least I HOPE that's what TurboTax will do).
90 minutes on hold and transferred around with the IRS and 45 minutes making sure I completed the right form with my brokerage got me to the above answer, and the penalty is now removed from my TurboTax return.
I hope this helps other people 🙂
