Unable to shut down MySQL server
Ideally you can shutdown using 

/etc/init.d/mysqld stop 


I cannot add comments so requesting to post what do you see in error log when you do

mysqladmin shutdown 


About kill commands please note that mysqld_safe is wrapper script which will start mysqld upon killing... so you should kill mysqld_safe first followed by mysqld. ( not a suggested way though).

Refer: how to stop mysql on mac