To achieve full compliance, Data Masker can delete field history. This setting needs to be enabled.

1. To enable this setting, Go to the  Setup -> User Interface.  “User Interface” will appear in search results as shown below screenshot.

2. Scroll down to the option below and check the check box if not checked already.

i.e Enable ‘Delete from Field History’ and ‘Delete from Field History Archive’ User Permission.

Now Click on the “Save” button.