Js中，怎么删除局部变量啊

我用delete,在严格模式中不能用

function JSONRpcClient_poolReturnHTTPRequest(http)
{
    if(JSONRpcClient.http_spare.length >= JSONRpcClient.http_max_spare)
    delete http;--删除局部变量http
    else
    JSONRpcClient.http_spare.push(http);
};