How to stop xampp mysql server?

I just installed xampp on my mac os x. When I tried start mysql it displays a message that mysql is already running on this computer. In order to start mysql stop first mysql. I tried following ways to stop it but neither of them works.

mysqladmin version
sudo /usr/local/mysql/mysql.server stop //mysql.server command not found
mysqladmin -u root -p password shutdown //restarts the server but not shutdown

when i use which mysql command it shows this path

/usr/local/bin/mysql

and when I issue ps aux | grep mysqld command I get following output

zafarsaleem    85209   0.0  0.3  2699804  13204   ??  S     7:51AM   0:00.88        /Applications/MAMP/Library/bin/mysqld --basedir=/Applications/MAMP/Library --datadir=/Applications/MAMP/db/mysql --plugin-dir=/Applications/MAMP/Library/lib/plugin --lower-case-table-names=0 --log-error=/Applications/MAMP/logs/mysql_error_log.err --pid-file=/Applications/MAMP/tmp/mysql/mysql.pid --socket=/Applications/MAMP/tmp/mysql/mysql.sock --port=8889
zafarsaleem    85093   0.0  0.0  2435488    924   ??  S     7:51AM   0:00.03 /bin/sh /Applications/MAMP/Library/bin/mysqld_safe --port=8889 --socket=/Applications/MAMP/tmp/mysql/mysql.sock --lower_case_table_names=0 --pid-file=/Applications/MAMP/tmp/mysql/mysql.pid --log-error=/Applications/MAMP/logs/mysql_error_log
zafarsaleem    86693   0.0  0.0  2425480    180 s004  R+    8:30AM   0:00.00 grep mysqld
zafarsaleem    86507   0.0  0.3  2678756  11364   ??  S     8:07AM   0:00.63 /usr/local/Cellar/mysql/5.5.20/bin/mysqld --basedir=/usr/local/Cellar/mysql/5.5.20 --datadir=/usr/local/var/mysql --plugin-dir=/usr/local/Cellar/mysql/5.5.20/lib/plugin --max-allowed-packet=32M --log-error=/usr/local/var/mysql/Zafars-MacBook-Pro-2.local.err --pid-file=/usr/local/var/mysql/Zafars-MacBook-Pro-2.local.pid
zafarsaleem    86447   0.0  0.0  2435488    920   ??  S     8:07AM   0:00.02 /bin/sh /usr/local/bin/mysqld_safe --max_allowed_packet=32M

How can I resolve this issue?

UPDATE

When I issue this command launchctl list then I do see mysqld in the list as follows

com.apple.AddressBook.SourceSync
-           0      com.apple.AddressBook.abd
1201    -   homebrew.mxcl.mysql                    <--
443         -   homebrew.mxcl.mongodb
-           0   com.google.keystone.user.agent
-           0   com.adobe.ARM.df0ab5bbe6f698196fcc21e3c1e66dcb758bd911f4d637272d9d8109
-           0   com.adobe.AAM.Scheduler-1.0
45          -   0x7fd1bba073e0.anonymous.loginwindow
-           1   com.apple.launchctl.Aqua
1261    -    0x7fd1bba0c6e0.anonymous.mysqld        <--
 212    -   0x7fd1ba5206d0.anonymous.launchd
 230    -   0x7fd1ba5203d0.anonymous.Terminal

Secondly when I tried to issue below command as mentioned by @PunjCoder

sudo launchctl unload -w /Library/LaunchDaemons/org.macports.mysql.plist
OUTPUT for above is:
launchctl: Couldn't stat("/Library/LaunchDaemons/org.macports.mysql.plist"): No    such file or directory
nothing found to unload

sudo launchctl unload -w /System/Library/LaunchDaemons/org.macports.mysql.plist
OUTPUT for above is:
launchctl: Couldn't stat("/System/Library/LaunchDaemons/org.macports.mysql.plist"): No such file or directory
nothing found to unload

So what can I do to stop them and how? I am very new to mac os x so don't really know how to resolve this issue. Please help...

Your MYSQL instance that is running is here /Applications/MAMP/Library/bin/mysqld (the MAMP one) and here /usr/local/Cellar/mysql/5.5.20/bin/mysqld (the one installed using Brew).

Try:

/Applications/MAMP/Library/bin/mysqladmin shutdown
/usr/local/Cellar/mysql/5.5.20/bin/mysqladmin shutdown

Then start the one you want to start. You also would want to check Library/LaunchDaemons/ for any launch scripts and use something like

sudo launchctl unload -w /Library/LaunchDaemons/org.macports.mysql.plist

Update: Please list the output of following commands: ls /System/Library/LaunchDaemons/ | grep mysql ls /Library/LaunchDaemons/ | grep mysql ls ~/Library/LaunchDaemons/ | grep mysql