Form I-407 may be filed by individuals who are outside of the United States.
Filing by mail:
The decision to abandon LPR status is strictly voluntary. If you wish to abandon your lawful permanent resident status, you are encouraged to directly file Form I-407 by mail with an USCIS Eastern Forms Center at the address below.
USCIS Eastern Forms Center
Attn: I-407 unit
124 Leroy Road
PO Box 567
Williston, VT 05495, U.S.A.
Note: Beginning July 1, 2019, USCIS will no longer accept Form I-407, Record of Abandonment of Lawful Permanent Resident Status at international field offices by mail or in person.
For details, please visit USCIS website: https://www.uscis.gov/news/alerts/uscis-will-no-longer-accept-i-407-international-field-offices