** Using WeBWorK **

You can certainly allow guests to submit answers. I beleive that that is the permission here: https://github.com/openwebwork/webwork2/blob/master/conf/defaults.config#L709 although as you can see there are a lot of things you can fiddle with with regard to recording answers and permissions.

There isn't a way to "reset" practice users at the end of a session. In order to have that functionality you would need to add something which deletes user data when logging in a practice user.