In order to remove a neutron you have to fire a projectile into the nucleus to dislodge the neutron.  The thing is, you can't be sure of the structure of the nucleus and where exactly the protons are and where exactly the neutrons are.  As a result, you can't guarantee that you will eject a neutron if you fire a particle or beam of energy at the nucleus.  Imagine the nucleus as a hodge-podge of two different colored spherical magnets.  The protons are red and the neutrons are blue.  They are both the same size.  Now you take a whole bucket of the magnets and blindfolded you reach your hand into the bucket and grab a handfull.  After taking your handful of red and blue magnets you count the number of red spheres (protons) and the number of blue spheres (neutrons) that are affixed to each other.  (You basically calculate the mass of the isotope you have).  Now take this mass of protons and neutrons and suspend it in a stream of upward moving air so that it kind of "floats" on top of this stream of air.  Get in a car and drive about a football field's length away.  Now take out a gun that fires small little bee-bees at the spinning "nucleus" at the other end of the field and accurately knock off only ONE neutron.  See the problem?

The nucleus is so small and the particles arranged in such a random manner that you can't accurately predict what you'll be knocking off.  In addition, because of the attraction between the particles, you have to use either a large projectile, or a projectile with a lot of energy.  The projectile with a lot of energy will undoubtably break the nucleus apart into many fragments (fission), or will be so massive that it won't knock off just one particle.  If you don't fire it with enough energy, it will just bounce off the nucleus or become absorbed by the nucleus.

Well, in reality it is not as hard - some elements/isotopes ARE produced by bombarding with neutrons of correct energy and mass of the produce is weighted in kilograms (if not stones). But  it is not an easy task.

We better wait for Mitch to enlight us

I think the OP was asking about why can't we take Element A with a mass of 161 and turn it into Element A with a mass of 160.  That's not something that can be done at the moment and I was trying to explain that to him.  I know we can produce certain isotopes of certain masses, but that is by ADDING neutrons to it.  I don't know of any that we make by subtracting neutrons from it.

   My question is why it isnt possible to reverse the proceeding. To have: C0-60 to Co-59 etc. Why we cant take back with some method a netron and have for e.g: From Co-60 to Co-59 etc. Is this possible to hapen in future?
    Thanks

You can see for yourself with scripts that I've made for this website. http://www.chemicalforums.com/index.php?page=scripts#Nuclear%20Reactions%20Calculator

The script says it gives -6.6825953480029 MeV for that reaction. So you need to put in that much energy for it to occur. Have fun playing with it I do.

Just shoot the nucleus with a gamma ray with that energy and higher and you'll get your product. You'll also get other junk, but you'll be making Co59.