If you wish to delete your history, go to “Profile” >“History” and click on the trash bin icon on the top right corner.
If you wish to delete your history, go to “My lists”. Browse till the end on “Continue watching” and click on “See more”. There, you will have the possibility to delete a specific item on the list or empty it altogether. Bear in mind that deleting the list will also remove it from your recommendations until you start watching something new.