PHP Manual: De-allocate a color for an image

bool imagecolordeallocate(GdImage $image, int $color)

De-allocates a color previously allocated with imagecolorallocate or imagecolorallocatealpha.

image: A GdImage object, returned by one of the image creation functions, such as imagecreatetruecolor.
color: The color identifier.

Returns true on success or false on failure.

Version	Description
8.0.0	`image` expects a GdImage instance now; previously, a valid `gd` resource was expected.

Example #1 Using imagecolordeallocate

<?php
$white = imagecolorallocate($im, 255, 255, 255);
imagecolordeallocate($im, $white);
?>

imagecolordeallocate