I am trying to file my taxes for free and I am being told I have to upgrade because "You have Retirement Savings Contribution credit" Why?

Just deleting the Form 8880 does not change the situation that made you eligible for the credit in the first place.  Therefore, TurboTax is trying to get you every credit you are eligible to receive.  

Since you are eligible for the credit, the only way to prevent the credit from being claimed on your return is to indicate that you were a full-time student.  This will make you ineligible to receive the credit.

Use the following steps to go through that section of your return:

• On the top row of the TurboTax online screen, click on Search (or for CD/downloaded TurboTax locate the search box in the upper right corner)
• This opens a box where you can type in “saver's credit, form 8880” (be sure to enter exactly as shown here) and click the magnifying glass (or for CD/downloaded TurboTax, click Find)
• The search results will give you an option to “Jump to saver's credit, form 8880”
• Click on the blue “Jump to saver's credit, form 8880” link