your old coin will have zero demand and no one has heard of it unless it is used in scam it can be reused, but this option is useless.
your coin value will almost zero and creating new coin is risky if you dont have any rood map plan or thinking to solve a system that solve real finance problem or be a unique project.

The developer will scam you if you pay him all the salary in one go, and the algorithm approval may determine your earning Staking/ dev coins/ Airdrop/ POS or whatever.

You cannot delete your smart contract coin if it is included in the block.