Want To Terminate Employee On Poor Perfomance

Usually all under performers are far superior performers in different perspective... you just need to locate what that other perspective is... else it's does not remain a human relationship job... it's turns otherwise..
just my opinion
you putting in extra thought will earn extra mileage for you (& your organization) in the long run... if you (& your organization) are in there for the long run i.e.

Dear All
Please understand "poor performance " is a a very generic word.Better not resort to this. If the Contract provides for notice period better use that.Always remember termination without casting aspersions on another is the best way for the Management.
With Regards