Okay, so it's not related to the CKeditor at all? I was confused by that. My guess is that you are talking about fields on the Blog pages, right? If that is the case, you should do next:
- Go to the Page types application
- Edit your Blog post page type
- Navigate to Fields tab on the left
- Select section Post to Facebook and then uncheck Visible field
- Repeat previous step for Post to Twitter and for Post to LinkedIn
It's better to hide them from the page instead of delete them, because maybe you will need them in the future.