Delete saved locations

you can delete them in Garmin Explore mobile. Then you even don‘t have to delete them if you wish to keep them, but just wish to remove them from the watch. In GE you decide which folder should be synced with the watch. The saved locations which you don‘t want to have on the watch can be moved to a folder which will not be synced with the watch. And if you no more need the saved locations you can delete them with GE all at once.  

But I guess I would need to sync my watch with Garmin Explore. I used GE years back but it wasn't really handy to use. Does it support routing or does it still just connect points with straight lines?

GE mobile is much better than year back. You can use it for routing. And you can use it for administer your activities and waypoints. I have ~ 4000 items in GE. Important is that you sync with the watch only the necessary items. 

Am PC den Inhalt im Order Location löschen und fertig 

Impressive, still don't like the web version but the app is great. Thanks 

Just synced accidentally >65000 waypoints. My watch almost died.