You do not have to file an amended return. The question about the withdrawal being an RMD just tells TurboTax whether the withdrawal is eligible to be rolled over. The answer does not appear on your tax return.
What you said about the letter from the bank, and your status with regard to RMDs, is not clear. You do not have to take an RMD until the year that you turn 72. What is your exact date of birth?
I assume that when you say "deduction" you mean a distribution or withdrawal from your IRA.
