Yeah, the bots can really crush the price of a token, especially if there isn't a lot of volume or liquidity. My !lolz token is in a pool with MEME, and at one point the bots came in and really crushed the price of LOLZ. But they can also help add support if folks use the swap to buy !bbh

Regarding ending one, I don't think you can. Once the smart contract is created it just keeps going and going.