What are your rights lawfully?

what if you received a doent that stated your employer was getting rid of you to lower their percentages for your type-meaning if you were promoted from within due to your experience and years on the job your company plainly states that they hire from within but they want to lower their percentage of people like you but they say that its your poor job performance as to why they are firing you this month i was fired but according to the doent this was put into effect in january that i'd be fired by a certained date and that happened according to there plan what are my rights lawfully