You stated that you have already filed a federal tax return and have received the federal tax refund in the amount of $1,242. You stated that you received a Form 1098-T and now need to change the original tax return that you completed, filed and received the tax refund of $1,242.
The ONLY way to change a tax return that has been filed and accepted by the IRS is to complete an amended tax return, Form 1040X. The amended tax return can ONLY be printed and mailed to the IRS.
The specific instructions on how to start an amended tax return using TurboTax is shown in this TurboTax support FAQ - https://ttlc.intuit.com/questions/3402261-how-do-i-amend-my-2016-turbotax-online-return
If you just went back into your tax return and made changes without starting an amended tax return as shown in the TurboTax support FAQ, then you MUST remove all of those changes before starting an amended tax return.
If you need assistance with removing the changes you made to the original return or how to start an amended tax return then you can contact TurboTax support for real-time assistance. See this TurboTax support FAQ for the procedure to contact Support - https://ttlc.intuit.com/questions/3401489-how-do-i-contact-turbotax?jump_to=answer_5566005
