Demeljoch is one of the rarely visited peaks in Karwendel because of long ascent, no huts and not good public transport. However the views of Karwendel and Sylvensteinsee are breathtaking.
Ascent: The path goes on the forest path from the parking lot. Soon after the bridge, turn left into the woods, and follow the signs towards Demeljoch. The path is often very narrow and requires traversing steep grassy slopes, although it's not so difficult.
After the forest the view of Sylvensteinsee, Juifen, Guffert is so amazing. Soon after the forest, the path becomes flat and also goes down sometimes. Shortly before the Dürrenbergjoch the path gets steep again. From this point on, the route is very moderate to Demeljoch.
Descent: I recommend to follow the same path as ascent. Because the one we did (as shown here in the map), requires long flat walk on a bicycle path in the end before getting to the parking lot.