Assuming you scanned it to a picture (jpg, bmp) you can use any picture editor (like Photoshop or MS Paint) to wipe out the wrong information and replace it with the correct text.
A very good alternative might be to find or download a new blank form and fill that in correctly.
Hi, I am a 2nd year student in graduation. Recently I filled an admission form for final year admission but it came back to me after 2 days because I had entered wrong information. I want to edit the wrong information and I have scanned the form. I am looking for a good online site where I can upload the scanned document and convert same into an editable format. I don't mind paying. If any can point to a good site will be great & thanks in advance