I was reading the introduction to Ethereum Smart Contracts here
. At the end of the page, it says:The only possibility that code is removed from the blockchain is when a contract at that address performs the SELFDESTRUCT operation. The remaining Ether stored at that address is sent to a designated target and then the storage and code is removed.
Note that even if a contract’s code does not contain the SELFDESTRUCT opcode, it can still perform that operation using delegatecall or callcode.
How is this possible? What does it mean?