The message **We can't find products matching the selection.** comes from the file `/magento/vendor/magento/module-catalog/view/frontend/templates/product/list.phtml`. 

You need to override the `list.phtml` file in your custom module or theme to hide the message.

**Example:**

```
<?php
/**
 * Product list template
 *
 * @see \Magento\Catalog\Block\Product\ListProduct
 */
?>
<?php
$_productCollection = $block->getLoadedProductCollection();
$_helper = $this->helper(Magento\Catalog\Helper\Output::class);
?>
<?php if (!$_productCollection->count()) :?>

// ---------------------- comment or remove the below code ------------------------------
<div class="message info empty"><div><?= $block->escapeHtml(__('We can\'t find products matching the selection.')) ?></div></div>

<?php else :?>
    <?= $block->getToolbarHtml() ?>
    <?= $block->getAdditionalHtml() ?>
....
....

```

I hope this helps!