Source

File: wp-includes/class-wp-object-cache.php

public function delete( $key, $group = 'default', $deprecated = false ) {
		if ( empty( $group ) ) {
			$group = 'default';
		}

		if ( $this->multisite && ! isset( $this->global_groups[ $group ] ) ) {
			$key = $this->blog_prefix . $key;
		}

		if ( ! $this->_exists( $key, $group ) ) {
			return false;
		}

		unset( $this->cache[ $group ][ $key ] );
		return true;
	}