You need to cancel the ED visa properly first. I am in the process of doing it now for the second time. You can just leave without cancelling it (I had a mate who did that last year) but it can be a problem if you go to immigration in country to try and extend one of your 180 day stays. It won’t stop you from getting your DTV or from getting into the country though. My mate who didn’t do it properly is on a work permit now and it’s all fine but they did put up a small fuss about him not doing it properly. More of an annoyance for not following the procedure they like, rather than a black mark or anything.