Is it permissible to make use of products that are still fit for consumption, or to give them to the poor, even though the contract between the two companies stipulates the destruction of only the damaged products?

If something is fit for use and still beneficial, and there is an intention to dispose of it, there is no harm in taking it and benefiting from it; rather, it is advisable to do so. It is permissible to donate it or use it in a way you deem appropriate, while being careful not to incur any harm from it.