Identity identity = context.getObjectByName(Identity.class, identityName);
AttributeMetaData atd = identity.getAttributeMetaData("FIELD NAME");
if (atd != null) {
List metaList = identity.getAttributeMetaData();
if (metaList != null) {
metaList.remove(atd);
identity.setAttributeMetaData(metaList);
}
}
identity.setAttribute("FIELD NAME",null);
context.saveObject(identity);