Hello there,

Listen, you have not mentioned there in which Exam or University Application form you did mistake , because every Exam or university have different procedure to deal with such kind of mistake.

BUT ,in most of the time ,there is an option like correction window for such kind of mistakes.

Generally , after submission of application form or and completion of Registration procedure ,they will open the correction window for resolving such kind of Issus.

As I have asked ,you have not mentioned important points in your question so, its pretty harder to me to reply your query.

Hope I am clear to you

Thank you :)