NEED HELP PLEASE !- Droopy Anthelia update

[Trabby]

Okay, my anthelia went from looking bad to looking better , all but a few stalks , now it is dying. There are also some green striped mushrooms on the same rock. One of the mushrooms is stretching its foot towards the anthelia, the anthelia is shrivelled whitish brown and kinda skanky looking. Is the mushroom killing the anthelia??? OK so heres the issue what is the best way to remove the dying parts of the anthelia from the rock? I would say aprox 50% is needing to be removed. But I need to figure this out fast as I have only a small tank and I am worried about poisioning the water.