if the fundamentals are the same as bitcoin you can't just pick a random address on your own, the address has to match certain rules which is the base58 encoding with checksum.
like this:
you can find articles on how to do it with bitcoin and then change them to your altcoin:
https://en.bitcoin.it/wiki/Proof_of_burn
http://bitcoin.stackexchange.com/questions/1851/how-to-generate-a-valid-bitcoin-address-for-destroying-bitcoins

p.s. donating them would be wiser and easier!