final Object entity = entityExpression.getValue(elContext);
final Object oldValue;
if (entity instanceof TaskInstance) {
final TaskInstance task = (TaskInstance) entity;
oldValue = task.getVariable(name);
task.deleteVariable(name);
} else if (entity instanceof Token) {
final Token token = (Token) entity;
final ContextInstance contextInstance = token.getProcessInstance().getContextInstance();
oldValue = contextInstance.getVariable(name, token);
contextInstance.deleteVariable(name, token);