I have an certificate that is really important for me and it has my name written on it, but the problem is the surname is mistakenly written wrong. I want to erase the blue gel ink from it and re-write my correct name.
I would guess the certificate would no longer be valid if tampered with. And I don't see any way of removing gel ink.
Can you consult the organization that issued the document and ask if they can issue another?
Mistakes can happen when you are preparing a document. Depending on the type of ink used there may be a way to correct the error. This is a page about removing ink from a document.
Isopropyl alcohol is usually the best way to break down ink, however it does depend on the type of ink. Removing ball point pen from paper can be a very difficult task but it's not impossible.
This is a page about removing ink from book pages. Removing ink from paper, without damage, can be very difficult if not impossible.