In JBoss, our deletes work differently. You need to create an <uninstalled> section in your xml. Then, simply move the <HellowWord> element and its childrend to the <uninstalled> section.
Because emost JBoss users are already familar with the xml config files, we leverage the existing JBoss XML instead of creating our own xml schema to represent JBoss configuration. For that reason, we do deletes differently in JBoss.