hi
for this we can do 2 slutions
1. same as vivek -go to se16n and do debug with the help of ABAPer and delete from back end
but se16n is the transaction code that we dont touch.
2.change the employee hiring date to 13.11.2013 and delete the record.and after that change the hiring date to original date.(if your not generating quota trough Time Evaluation).
Regards,
Sajid Ali Khan.