web-server/data/release/security/usergroup/default/users.xml

<?xml version="1.0" encoding="UTF-8"?>
<userRegistry version="1.0" xmlns="http://www.geoserver.org/security/users">
    <users>
        <user enabled="true" name="admin" password="digest1:D9miJH/hVgfxZJscMafEtbtliG0ROxhLfsznyWfG38X2pda2JOSV4POi55PQI4tw"/>
    </users>
    <groups/>
</userRegistry>