Short answer. You must file it in person. Republic Act 9048 allows only a person with a direct and personal interest to file the correction, and it requires the verified petition to be filed in person with the local civil registrar. You cannot simply send a relative or messenger to lodge it for you.
What the law says
may file, in person, a verified petition with the local civil registry office of the city or municipality where the record being sought to be corrected or changed is kept
RA 9048, Section 3 — Who May File And Where. Read the full provision →
The statute says 'in person'
The law is written from the side of the person seeking the correction, and it is unusually blunt about presence. It provides that any person having a direct and personal interest may file, in person, a verified petition with the local civil registry office of the city or municipality where the record being sought to be corrected or changed is kept. The words in person are repeated for every route the section allows, which tells you the requirement is deliberate, not a stray phrase. This is an administrative correction handled by the registrar, so the law keeps the applicant physically before the office that holds the record.
Where you file if you have moved or live abroad
The section does bend for distance, but never on the in-person point. If you have already migrated to another place in the country and travelling back would be impractical in terms of transportation expenses, time and effort, you may file in person with the local civil registrar of the place where you now reside, and the two registrars communicate to process the petition. Filipinos residing or domiciled abroad may file in person with the nearest Philippine Consulate. In each case the flexibility is about which office you attend, not whether you must attend one yourself.
What this route does not let you do
Because filing is personal, this fast administrative track is not a way to have a lawyer or agent quietly process a record change on your behalf without you. It also carries a hard limit the section states plainly: petitions for clerical or typographical errors and change of first name may be availed of only once. That single-use rule means a careless or incomplete first petition can cost you the administrative remedy entirely. The requirement of a direct and personal interest also blocks strangers from tampering with someone else's civil record, which is part of why the presence rule exists.
What to sort out before you go
Practically, the personal-filing rule means planning the trip and the papers together, since you cannot delegate the appearance. Confirm which registrar holds the record, gather the supporting documents the law separately requires, and be ready to swear to the petition, because it must be verified. If the entry you want changed is not a simple clerical or typographical error or a first-name change, for example a change that affects nationality, age, status or a person's identity, a different and usually court-based procedure applies, and no amount of personal filing at the registrar will substitute for it. When in doubt about which track fits, have the record reviewed before filing.