Sometimes when we try to edit our header names and change the name to some other name, we may face this error, 'Disable 'Combine column Headers' to edit column headers':
To rectify this error, you can go to the Display tab located under the Home tab and remove the Combine Column Headers feature like shown below:
Once you have disabled Combine Column Headers feature you can now you can edit the header names and change them to whatever name you want:
