How i can delete last block from blockchain? altcoin How can I delete the last block from blockchain to be ready for hardfork.
What I mean is, in blockchain last block is with error's. I want to delete those blocks, for the new blockchain is disabled from the last block. 


How can I mine new block if last block would be 1 day old? How do I understand that the daemon does not start giving work to pool/miner, if last block is very old? They will be trying to find new block's from peer, even if it does not exist ?
You can't delete a block, just mine a new block on top of the previous block, creating a fork. Just reference the parent block as the parent of your new block, and if you mine more on top of your new chain, it will become the accepted chain.
The age of the block shouldn't matter.