I have a Windows Server 2012 running Couchbase Server and Sync Gateway. I am able to access the Sync Gateway locally, but am unsure how to reset a user account password. I have been able to add a new user via the Admin API on port 4985.
To change a user account password send PUT to the user account.
$ curl -iX PUT http://localhost:4985/default/_user/myuser --data
'{"email":"myuser@gmail.com", "name":"myuser", "password":"NEW_password",
"admin_channels":["myuser", "public", "NEW_channel"]}'