When you receive e-mails of task we can directly access the link in the e-mail. These e-mail has a user's information, the token. We can hide these data token for security?
activeCollab does not include user token for these links. You are probably using a third party module that modifies URL-s used in email notifications and adds a token. You should disable it if you don't want token to be included in the notifications.
Module administration is available on Administration > Modules page. You can see list of installed modules and uninstall the ones that you do not need. I'm not sure which module is adding these links, but you can check the list of modules that we ship with activeCollab on Pricing page and see which modules are added on top of that setup.
@FernandoOne - Not sure without knowing more but this sounds like it might be the Auto Login module from www.uswebstyle.com if it's allowing automatic login from the URLs in the Email Notifications. This is part of their Modules Bundle
I'm sure they would love to hear your feedback on this, and could present some options to address your concerns. It should be listed in your Modules list and be available to uninstall if needed.