Upvote:3
Go to https://esta.cbp.dhs.gov/esta/ and click "Check existing application", "Check individual status", "Confirm".
Type in your passport number and ESTA confirmation number, or click "I do not know the application number" and type in name and citizenship too.
If you find a valid ESTA, there'll be an "update" link (not a button!) in one of the last columns of the table.
Note that you're not actually required to keep the "address in the US" information up-to-date after the ESTA is approved.