关闭账户可让您重新获得用于开立账户的 SOL，但需要删除账户中的所有信息。关闭账户时，请确保在同一指令中将数据清零，以避免有人在同一交易中重新打开账户并访问数据。这是因为在交易完成之前，账户实际上并未关闭。

use solana_program::{
    account_info::next_account_info, account_info::AccountInfo, entrypoint,
    entrypoint::ProgramResult, pubkey::Pubkey,
};

entrypoint!(process_instruction);

fn process_instruction(
    _program_id: &Pubkey,
    accounts: &[AccountInfo],
    _instruction_data: &[u8],
) -> ProgramResult {
    let account_info_iter = &mut accounts.iter();

    let source_account_info = next_account_info(account_info_iter)?;
    let dest_account_info = next_account_info(account_info_iter)?;

    let dest_starting_lamports = dest_account_info.lamports();
    **dest_account_info.lamports.borrow_mut() = dest_starting_lamports
        .checked_add(source_account_info.lamports())
        .unwrap();
    **source_account_info.lamports.borrow_mut() = 0;

    source_account_info.assign(&system_program::ID);
    source_account_info.realloc(0, false).map_err(Into::into)

    Ok(())
}

https://solana.com/zh/developers/cookbook/accounts/close-account