Is it permissible to expel a treacherous partner who harms vulnerable workers from a partnership by means of deception?

Your question about betrayal is general. If the partners find that a partner's action harms the company and they wish to dissolve his partnership, there is no blame upon them. Partnership is one of the permissible contracts that either party has the right to dissolve at any time.

As for canceling the contracts of some workers for the reasons mentioned, it is not permissible to deceive them. Rather, it might be in the company's interest. The matter should be presented to the remaining partners. If they agree to cancel their contracts, it is permissible, and their provision is upon Allah the Almighty, for He is the Provider who guarantees the provisions of His servants, as confirmed by His saying, the Almighty: "And there is no creature on earth but that upon Allah is its provision, and He knows its resting place and its depositing place. All is in a clear register." And the saying of the Prophet, peace be upon him: "O people, fear Allah and be moderate in seeking [provision]; for no soul will die until it has received its full provision, even if it is slow in coming to it."