Hi, welcome to Google Chrome Help Community.
Yes there is. You may please open
chrome.google.com/sync and sign in with the account with which your father's Chrome account is being synced. You will see statistics of all the information Chrome has stored to the Google Account. At the bottom of the page, you'll see a Delete data button. You can clear all the data that has been synced by Chrome to that account there.
Please note that this will also delete saved passwords, bookmarks, etc. So, please make sure to take a backup of your bookmarks and saved passwords before you proceed. After cleaning all data, you can use the backups to reload the saved passwords and bookmarks.
Best.