I closed out a 529 College Choice Plan in 2018 and the account shows a final loss of $995. Can I deduct that investment loss and if so, how do I do that in TurboTax?

No, unfortunately the loss on an education savings account can not be claimed. 

According to the IRS:

"Losses on Coverdell ESA Investments

For tax years beginning after 2017 and before 2026, if you have a loss on your investment in a Coverdell ESA, you can’t deduct the loss on your income tax return. You have a loss only when all amounts from that account have been distributed and the total distributions are less than your unrecovered basis. Your basis is the total amount of contributions to that Coverdell ESA."

https://www.irs.gov/pub/irs-pdf/p970.pdf