You will have to delete the W-2 entry and enter the 1099-R please follow the instructions below.

To delete the W-2 entry:

1. Login to your TurboTax Account 
2. Click "Take Me To My Return"
3. Click "Federal" from the left side of your screen
4. Scroll down and click "Start or Edit/Add" next to “Job (W2)”
5. On the "Here's your W-2 info" screen click on the "trash icon"

To enter the 1099-R:

1. Click "Federal" from the left side of your screen
2. Scroll down to “Retirement Plans and Social Security” and click “Show more”
3. Scroll down and click "Start" next to "IRA, 401(k), Pension Plan Withdrawals (1099-R)" 
4. Answer "Yes" to the question "Did You Have Any of These Types of Income?"
5. Click "I'll Type it Myself"
6. Choose "Form 1099-R, Withdrawal of Money from 401(k) Retirement Plans, Pensions, IRAs, etc." and select whom the form belongs to.
7. Click "Continue" and enter the information from your 1099-R