Out of Memory problem

try increasing memory available for php.

Done with
define( ‘WP_MEMORY_LIMIT’, ‘250M’ );
in wp-config.php . now when I enter into admin panel, it shows following!

Fatal error: Out of memory (allocated 133955584) (tried to allocate 491520 bytes) in /home/techgain/public_html/wp-content/plugins/genesis-toolbar-extras/includes/gtbe-themes.php on line 623

try disabling/renaming “genesis-toolbar-extras” plugin folder via FTP

Now what is this?

Warning: Cannot modify header information – headers already sent by (output started at /home/techgain/public_html/wp-config.php:2) in /home/techgain/public_html/wp-includes/pluggable.php on line 896

You have introduced an error in your wp-config.php file. Try reviewing Solving “headers already sent” warnings.

Fixed about space before “?php” .
But I don’t find any last characters “?>”

But I don’t find any last characters “?>”

?> at the end of wp-config.php is left out purposely.

OKay…
Now again this error >

##
Fatal error: Out of memory (allocated 130809856) (tried to allocate 1835045 bytes) in /home/techgain/public_html/wp-includes/functions.php on line 336
##

Question:
In wp-config.php, where I should write the such following code?
define( ‘WP_MEMORY_LIMIT’, ‘250M’ );

And should I add it in wp-setting.php too?

Now, what I found is, WPSEO plugin is making this problem. Enabling or Disabling this plugin makes the site show the error or fix!
But I need to use that plugin! How do I fix it?