As whywaitforit says depends how bad it is.
if its only a couple of spots then heres a method used quite frequently by growers.
crush them between your forefinger & thumb ,then get a mister (spray bottle) fill with cold water then get the effected plants & blast them with the mister all over the effected area ,washing them off, now get a sponge & cut in half (or get 2 sponges

) ,now put sponge underneath leaves effected & with the other sponge wipe ,firmly but carefully, the excess weater off, cleaning the sponges every time you wipe.
this will work.
if more than a couple of leaves effected then i'd recommend "stay safe" it works on all pests very quickly, just spray all over plant, leave & re-spray again 4-7 days later, job done.
can get at most good hydro stores
this'll work too.
hope this helps bud