Drop sg to 1.009 .Be sure to use a well calibrated refractometer. The fish have an internal salinity of 1.008. I f you slip below that you will do harm to them. If you stay too high the hypo will not kill the crytocaryon irritans parasite.
You can go down fairly quickly. A two day period should be ok for your denitrifying bacteria to adjust( most live 24 to 48 hours) and new strains will adjust o lower sg. The fish do not have to do anything to adjust except drink less water so there is no stress on them. Any invertebrates will die in this low salinity, this includes pods, corals, shrimp, crabs, etc. Watch ammonia closely since die off inside the rock may cause a spike at a time when your bacteria are adjusting.I would do this realtiovely soon to bar a reinfestation which will be much worse than the original infestation.
When you go back up raise the sg a point a day to avoid stressing the fish who do now have to work pretty hard to readjust to the higher sg.