You can make changes to the root crontab with the following procedure.
The root crontab allows you to schedule a script to run at specific times. Only scripts that perform system administrative tasks should be included in the root crontab.
Use the following command to list the existing crontab:
crontab -u root -l
If some or all of the cPanel specific cronjobs are missing you can learn how to replace them in the following article:
How to create missing cPanel cron jobs
To edit the root crontab use the following command:
crontab -u root -e