This article describes how to completely delete call records from your phone. You may be asked to remove call records from a phone to protect the privacy of another party.
For iPhones:
See the Apple article "View and delete the call history on your iPhone".
Delete all iCloud backups of your phone from the period after the call was made, using the instructions in this article: View and manage iCloud device backups.
For Android phones:
See the Google article "Manage call history & do a reverse phone number look up."
Go to https://drive.google.com/drive/u/0/backups (while logged in as the Google account your phone uses) and delete any backups from the period after the call was made by right-clicking and selecting "Delete backup."
For other phones:
For all other phone types, contact the Helpdesk for guidance.
Questions?
Contact Support