Is money earned from a company established recently, after a previous partnership was dissolved in an unclear manner – by claiming that the shop owner took back his computers and then leased them individually – halal or haram?

There is no blame upon you for what you did in dissolving the partnership and undertaking the work alone, because a partnership contract is among the permissible, non-binding contracts. It is permissible for either partner to dissolve it, especially after the capital has been exhausted and the work completed. As for your telling your partner that the shop owner wants to reclaim his shop and computers, if it was a lie, then it is forbidden, and you must repent from it, but that does not affect the lawfulness of your work.