Only a very select few dwarf angels, like Venustus angels, which actually were only recently reclassified as Centropyge, eat sponges. Almost all dwarfs feed on a diet of filamentous algae in the wild.
To get rid of the q-tip sponges, just give your tank a bit more time to mature. They are a part of any tank's life cycle, and for the meantime, they're beneficial filter feeders.