How do I (24f) change my dependency status after I filed and got rejected because my mother claimed me when she said she wouldn't?

Not so fast.....provide some details.   If you were 24 at the end of 2023-----did you earn more than $4700 in 2023?  If so---no one can claim you as a dependent.   If you earned less than $4700 and your parent supported you, then you can still be claimed as a dependent.

We do not have enough information to determine which one of you made a mistake and who needs to change their tax return.

Q.  How do I (24f) change my dependency status after I filed and got rejected?

A. Go to the personal info section.  Click edit next to your name.  Change your answer to the Can you be claimed as a dependent question.

That's how you do it. The bigger question is should you do it.  It you were not a full time student for parts of 5 calendar months in 2023 and you made more than $4700, you cannot be  dependent.  You will have to paper file your tax return and mother will need to file an amended return unclaiming you.  You do not need to wait for her to amend, but you cannot e-file.

Irrelevant tidbit: With the tax law change, effective 2018, most dependents will get the same refund whether they claim themselves or not. The personal exemption has been eliminated and the standard deduction increased. However, you only qualify for an education credit or deduction, if you are not a dependent.