ps -ef
#you will see the proces now, then
kill -9 PID
###########################################
if there are so many backgroud process, kill them using follwing script
#!/bin/bash
while :
do
echo "Press [CTRL+C] to stop.."
for pid in $(ps -ef | awk '/your process name/ {print $2}'); do kill -9 $pid; done
# credit to above answer
sleep 1
done