You can delete places from your Maps history one at a time, but not all at once.
You can delete all of your search history from Maps at google.com/History, but this doesn’t include places you’ve saved, shared, or dismissed suggestions to review.
To delete a place from your Maps history:
Open the maps Google Maps app and sign in.
Touch the side menu > Settings > Maps history.
Touch the X next to the entry you want to delete, and then touch Delete.
Deleting your Maps history won’t free space from your phone or tablet’s storage. To do this, you need to clear application data from Google Maps.