That error is normally something for your hosting company to fix, by raising the amount of RAM available to a PHP process.
This is from my own /etc/php5/apache2/php.ini file:
You might be able to edit your own PHP memory_limit by placing this line in your .htaccess file:Code:memory_limit = 1024M ; Maximum amount of memory a script may consume
This plugin appears to be asking for more than 536,870,912 bytes of RAM. Can you try to a less massive delete?Code:php_value memory_limit 1024M