public synchronized void remove(final K key) {
        final Pair<GeoItem, Boolean> value = itemMap.get(key);
        if (value != null) {
            itemMap.remove(key);
            if (value.second) {
                removeFromMap(key, value.first);
            }
        }
    }
Removes an object from this layer
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/GeoItemLayer.java