You can use it as an incense or crush them and use them in your potions and brews. You can even infuse them in to your essential and carrier oils. Sprinkle a little on top of your ritual candles or throw a handful in to a ritual bath. My favorite way (besides drinking them in a tea) to use these beautiful flowers is to adorn my altar with them. 
 
They are sacred to the Indian Elephant God Sir Ganesh. In traditional Witchcraft and Energy work Hibiscus represents Freedom, Harmony and Relaxation, Independence, Passion, Romance, Sexual Desire, Swift Assistance and Activation.