To remove the “?___store=default” from your Magento URL, you can follow these steps:
By setting “Use SID on Frontend” to “No” and “Use Web Server Rewrites” to “Yes”, Magento will generate clean URLs without the “?___store=default” parameter. This will also help to improve your Magento website’s search engine optimization (SEO) by making your URLs more user-friendly and easier to index by search engines.
Note that if you are using a custom theme or third-party extensions, there may be additional steps you need to take to fully remove the “?___store=default” parameter from your Magento URL. In that case, it may be best to consult the documentation or support resources for your theme or extensions for more information.