Magento – Strange gclid parameter in url

You can do this by "URL Rewrite Management"

Catalog->URL Rewrite Management-> Click "Add URL Rewrite" button Then Select "For Category" -> Select a category you want to rewrite to product page.

Then enter your product url in 4th field "Request Path". here hoodies.html is my product URL: http://localhost.com/magento/hoodies.html and then Select "redirect permanent 301" from the list "Redirect".

Go to the Store > Configuration > General > Web > Session Validation Settings > Use SID on Storefront and set its value to No

Here is the good answer about the SID:

The SID is a "session ID". Magento uses this to track a user's activity within the same Magento installation. Normally, Magento powers one website and one store from one installation (database).

Magento could power multiple websites with multiple stores from one installation though. The SID allows users to stay logged in while navigating across these websites/stores.

I think if you have the function enabled, the SID is sent when accessing catalog URLs so Magento can update the session with the user's location/state for the current website/store.

If you're not running a multi-website or multi-store environment, it's safe to disable the SID on the frontend.