Why not leave Yomiyama?
The deaths are tied to both members of class 3-3 and Yomiyama. My guess is that if you try to leave either class 3-3 or Yomiyama you'll be killed by doing so, rather than waiting for your turn to die through the normal means of the curse--one death every month.

This is mentioned in the show due to one of the character's deaths and on the wiki:


   Aya Ayano - While leaving Yomiyama with her parents in their family car, a rock fell and hit the windshield, causing her father to lose control and drive off the mountain.