To kill a process in Batch you can use the snippets below.
If you dont know how to retrieve the PID you can use our other snippet List all Processes in Batch.

Sample Batches

taskkill /PID 1292

if you want to force the taskkill you can use /F.

taskkill /F /PID 1292

if you want to taskkill the process by name you can use the follwoing snippet.

taskkill /im notepad++.exe

for more informations see the msdn TASKKILL