The rabbitmqctl command with the set_permissions option can be used to update a users account with certain permissions to certain objects. Before issuing the set_permissions command, you will usually want to use the list_user_permissions option to list the users current permissions.
You would use the -p option followed by a virtual host. In this example, virtual host / is specified. The last three options are:
rabbitmqctl set_permissions -p / john.doe ".*" ".*" ".*"
Something like this should be returned.
Setting permissions for user "john.doe" in vhost "/"