Hello @vestitigratis,

You can remove the product search form categories dropdown by customizing the theme via a child theme.

For reference on creating and using the child theme, please check the link here :

https://codex.wordpress.org/Child_Themes

You can also automate the task by using the Child theme generator plugin.

After creating and activating the child theme, create a new file “product-search.php” in your child-theme/template-parts directory and add the following code in the product-search.php file :

This will remove the category dropdown from the header product search.

Best Regards !!