Depending on how much salt is on them, and how it's been applied, you might be able to knock some of it off, and effectively decant it: Place the peanuts into a hard-sided container at least twice the volume of the peanuts that you can seal tightly.
Shake the peanuts.
A lot.
Not too hard, though, as the goal is to knock some of the salt off, not to smash the peanuts up.
Finish by shaking the peanuts side to side, or placing it on something that vibrates (like a washing machine) Open the container, and scoop the peanuts out, being careful to leave the excess salt at the bottom.
You save yourself some effort, you might be able to do the whole work on top of your washing machine, or leave the container in the trunk of your car for a few trips.
The larger the salt crystals, the easier this will be to remove.
If it was applied as a wet spray or while the oils were on the surface of the peanuts, it's going to bind more to the peanuts, and be more difficult to remove.
Although the diluting trick will work, you can also use the peanuts in a recipe that would have otherwise called for salt and leave out the additional salt.
You could also crush them up and use them as a topping for something that could use a little extra salt.
(ice cream, Pad Thai, etc.)
cooking.stackexchange.com/users/67/Joe
Remove all surface salt by quickly rinsing them and thoroughly drying them as fast as possible.
cooking.stackexchange.com/users/20118/Max
I have rinsed salted nuts well in water to remove the excessive salt and then dried in the oven.
Since salted nuts are already roasted, they don't "roast again" very well at all (or in general behave like raw peanuts when cooked) but you can certainly rinse to remove excess salt and dry at low temperatures.
If you want to just eat them immediately you can just eat them damp, but to preserve the quality or to use for something like peanut butter, they need to be dried again.
Getting them unsalted in the first place is more desirable, but not always feasible due to oddities of pricing (where unsalted nuts may cost 2-3 times as much as the same things with salt.)
cooking.stackexchange.com/users/34242/Ecnerwal
Bring a saucepan of water to the boil, then add the peanuts and a small potato and simmer for half an hour.
The salt will travel from the surface of the peanuts into the potato, which you can then discard.
Since the peanuts are for peanut butter, boiling them shouldn't affect the final taste, though you can try a lower temperature if you're concerned, or if you want to preserve crunchiness.
I used to use this method when boiling super-salty gammon steaks.
In this case, it should actually be more effective, since the salt is only on the surface of the peanuts, rather than begin suffused through them.
cooking.stackexchange.com/users/19367/John Gowers
You really can't un-ring that bell...
you can, however, dilute the "extra salty" peanuts with other, unsalted, peanuts until the you get the desired saltiness in your peanut butter.
cooking.stackexchange.com/users/6279/Cos Callis
You could put them in an industrial sifter and use that to knock the salt off and separate the peanuts from the salt in one step, but that's probably overkill unless you have a lot of nuts.
Instead knock the salt off first, either with the shaking method that Joe mentioned or by placing the nuts between two sheets of clean fabric or clean, food safe paper and rolling and gently scrubbing them.
Then do the sifting step using a normal kitchen sifter/strainer.
cooking.stackexchange.com/users/34973/user3067860
For eating in general, I took around 400grams of salted mixed nuts, followed Ecnerwal's and Charles Moore's Idea (thank you), rinsed it a couple of times, Preheat conventional oven at 350F, I used an aluminum foil sheet, and spread these nuts on them, Leave them for 3 mins, turned most of them with a couple of swipes with the hand, Leave them again for 3 mins and turn off the oven, Let it cool for 3-5 mins and take them to a plate and let it cool again, before you move them into an airtight container.
I prefer to do this few at a time, than the whole 2.5lb container.
Here are some pics. https://drive.google.com/open?id=0Bzj_F7fR53q6NnlfanpmUloyWlE
cooking.stackexchange.com/users/51985/raja777m
Wash, shake off excess water, put in baking pan, place in oven for 7 minutes at 350 degree, remove and let them set until cooled rebag and eat.
Now I want to know how much salt is retained in the nuts?
cooking.stackexchange.com/users/41843/charles moore
Put similar types of these two bowls together and shake them vigorously above a sink or any receiver and after few minutes most of the salt will be removed
cooking.stackexchange.com/users/67805/M Bah
I bought roasted peanuts from the market and they have too much salt in them.  How should I reduce the salt in those peanuts as much as I can?  My intent is to make peanut butter.
How to unsalt roasted salted peanuts?
cooking.stackexchange.com
<salt><peanuts><peanut-butter>
cooking.stackexchange.com/questions/56737
cooking.stackexchange.com/users/6168/Aquarius_Girl
You can try to sift away some of the salt or knock it off by shaking in a large container. Rinsing or boiling them can remove excess salt, and the peanuts can then be dried by heating in the oven for a few minutes. Alternatively, the salted peanuts can be mixed with unsalted peanuts. There are a number of methods recommended for removing excess salt from peanuts. These include washing with water and drying in the oven, mixing with unsalted peanuts and removing the salt in an industrial sifter.
Rinsing peanuts with water and then drying/baking in the oven is one way of removing excess salt. Diluting the saltiness of peanuts by mixing with unsalted peanuts reduces the overall saltiness. Put salty peanuts in anindustrial sifter to remove excess salt.