@mryoshisaid- You cannot at present swap the GMail email named Google account for another but you CAN change the name of the Google account you used to create your YouTube channel with if it was not GMail. :) This is because YouTube is no longer a standalone YouTube account as such- it is "only" a Google product which is controlled from the Google account people pick themselves.
THIS thread is for people who have older style accounts which ARE stand alone YouTube accounts which were accidentally linked. This is quite different.
While I understand that it is annoying to have to make sure that you pick the right account to create your YouTube channel to begin with it is not quite "billions" of users who change their minds about their Google accounts used. Most of those who have changed their mind just need to give their Google account another name, ie email address. :)