It's not that easy, depending on what you used they may be back in a few weeks. You have to make sure the eggs are dealt with as well and any future generations are dealt with.
The residue left by Permethrin will kill for a few weeks, and I would suggest another treatment in 3-4 weeks to make sure you kill off any hatching eggs. Something like Reptile Relief will do nothing against the hatching eggs and they will keep popping up and require numerous applications.
Your best bet is a preventative/treatment like PAM that will kill and prevent. Once they are gone, it's only a matter of keeping them out by quarantining any new snakes, treating substrates like Aspen bought in pet stores that tend to carry mites, etc.
Good luck.