Hi 

Odoo sometimes auto-installs certain apps when you use specific features. In your case, it may have been installed when you checked the email tracking options in CRM.

Since you're using the free single-app CRM version, uninstalling Link Tracker might not be possible without losing CRM, because Odoo enforces the single-app rule. You can check by going to Apps > Link Tracker and seeing if the Uninstall button is available.