On the page « my activity », you will find all the information Google collected on you through its different services : the search you make, the places you visited, the videos you watched.
1- Click on the main menu on the top left hand corner (burger menu) to make the menu appear and click on « delete activity by»
2- A window “Delete activity” opens. Click on “Always”
If it is not made already, select all Google services : Maps, Search, advertising Solutions, YouTube
3- a new window can then appear “Confirm that you would like to delete the following activity”. If it is the case, click on “delete”