How to remove an element from a PHP array if the key equals 'index'?

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I have this \[code\]$array\[/code\] in which the \[code\]index\[/code\] key could appear in any random order:\[code\]array(4) { ["foo"]=> bool(false) ["index"]=> bool(false) ["bar"]=> bool(true) ["biff"]=> bool(false)}\[/code\]Without adjusting the position of the elements or changing the key or value, how do I remove the \[code\]index\[/code\] element, resulting in a new \[code\]$array\[/code\]?\[code\]array(3) { ["foo"]=> bool(false) ["bar"]=> bool(true) ["biff"]=> bool(false)}\[/code\]