How do you delete or clear the Suggestions in Maps?

You can select Favorites by clicking in a blank search window (or hit Command-F keys and choose Favorites), then Recents from the list. You can then hit the Clear Recents button. This will delete all recent suggestions used before.

I agree on all points and could include a few others such as not being able to change routes or parts of routes. It is what it is for now.

Apple Feedback:

https://www.apple.com/feedback/maps_mac.html