Is it OK to kill the Dragon by skip the Dragon fight?

We were discussing that the other day and we have to check if skipping her gives you the achievement, but for now we believe you need to kill her because if you skip her she is still alive

The wiki says this (bedrock) The End In-game description: Kill the Enderdragon Actual requirements (if different): Enter the end exit portal.

https://minecraft.gamepedia.com/The_End#Achievements

but i found that if we skip the dragon and go to the portal again(idk how to say it...),the dragon will disapper.i don't know if that make dragon died or something...