This will remove the alias and add it to a different index


curl -XPOST 'http://localhost:9200/_aliases' -d '
{
    "actions" : [
        { "remove" : { 
            "index" : "bwuserp20171007t010432", 
            "alias" : "bwuser" }
        },
        { "add" : { 
            "index" : "bwuserp20170708t142611", 
            "alias" : "bwuser" }
        }
    ]
}'