The IRS can't fix it because they don't know whether you can be claimed as a dependent or not. You will have to prepare, print and mail an amended return form 1040X to make the change by unchecking the box that you can be claimed by someone else. Don't change your original return until you start the amended return. Here is a link to help you: https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
The amended return must be printed and mailed. It can't be efiled. You must print it yourself. TurboTax doesn't print and mail it for you. It takes the IRS about 16 weeks to process an amended return.