If zi-o erases history like they did with build then who stops evolt? Or is this another alternate universe version of build that got erased from history in episode 2. I can't move on until know wtf is the deal with erasing the another Rider and subsequently wiping the rider from existince.

Based on what was said in episode 2.5 (It's like the Build series never existed) and the events in episode 3, it seems like the Another Watches and the Rider Watches not only erase the Riders themselves, but everything related to them. In episode 3, while Another Ex-Aid is attacking people in the present, there seems to be no CR and Hiiro never mentions the game illness in spite of this mysterious state that only gamers fall into.

So, Evolt would get erased (if he were still around) right alongside Sento and Banjo forgetting everything Rider related.