It is not permitted for me to write this for you, as it is your assignment. However, I can give you some points that will help you to write the closing statement yourself.
If you had to prepare closing statement against Andrew Beckett, then you can make the following points.
First, since the trial is about wrongful termination, you need to argue that the termination was not wrongful at all. In other words, there is probable cause for the termination. In light of this, you should argue that Andrew's work was sub-par and caused the company hardships. The more evidence you have, the better your argument will be.
Second, you should also write that he deliberately withheld information to the partners of the law firm, which was important. Better yet, you should argue that he mislead the law firm. In this way, you can say that there was an ethical issue. Moreover, you can claim that this information was essential for the well-being of the company. In this way, his termination was acceptable.
Also you should deemphasize that the case was about discrimination in any way.