Well, as you correctly noted, you need a special tool for it, however I know there are some brokers which offer the opportunity to close all the opened trades at once, but of course you perhaps have other positions which you don't wnna close. So, in this case it's better to ask a broker whether it offers such a tool or not. Another option is to find a good tool or as you pointed EA, which might work the same way.
However, I believe there is no need to close multiple trades at once, because everything might be done by your own hands, the gap among the poisitions will be 1-2sec and I don't think it will be so crtical.