How to change google account associated to blogger?

Here's how you can transfer the account.

First, log in to Blogger.com with old Google account.

1. Click Settings 
2. Click Basic > Permissions > Blog Authors > Add authors. 
3. Enter the new email address as an author and Click Invite Authors.
4. Logout from your old Google account.

Now open the browser in incognito mode.

1. Login to Gmail using your new Google account and accept the invitation for the author.
2. Logout completely from all of your Google account. 
3. Log in again to Blogger.com using old Google Account.
4. Go to Setting > Basic > Permissions > Blog Authors > select Admin next to the name of the author.
5. Log out from Blogger.com.

Then login again to Blogger.com using your new Google account.

1. Go to Setting > Basic > Permissions > Blog Authors.
2. Click on X symbol next to the old email address to remove.