Thanks for clarifying you are using CrazyTalk 8. You posted in the CrazyTalk 6 forum which is why I wanted to check.
Any movement will come from either a Motion Clip, Auto-Motion or Idle pose.
Try changing the Auto-Motion Idle to the "Blank" clip. This will remove all movement from the Auto-Motion track. Then try removing motion clips one by one until you find the head swing movement stops If you remove all motion clips and the head is still moving then it could be a corrupt project. To check try with a new project to see if the issue reappears.
Peter
Forum Administrator
www.reallusion.com