According to 1xbit_official, it is not permitted to change your prediction. It is unfair to other players who are posting their predictions after you.
There were a couple of participants who were disqualified for it.
1xbit_official means you cannot
edit your post with regards to what you said above, But deleting your previous prediction and making another post is permitted because you are not messing with the people's prediction who've made it till now if I'm correct.
Maybe we should wait for 1xbit_official to add rule next time, looking at Drakrmaster's situation this time around.