The following command prints the second column in the output of processes which contains oraxpo in their name.
$ ps -ef | grep oraxpo | grep -v grep | awk '{print $2}' 4665 4667 4669 4671 4673 4675 4677 4679 4681 4683 4685 4687 4689 4691 4713 4715 4719 4735 4749 7720
Now all we need to do is to pass the result of this command to "kill -9".
$ kill -9 `ps -ef | grep oraxpo | grep -v grep | awk '{print $2}'`
NOTE: Please don't try this unless you have tried every thing else and there is no way else left then killing oracle like this.