You should open another form, or use conditional visibiltiy on the row containing the form, based on active userrole.

update So you want to close the form after logging in via the login form widget? That is done automatically, unless you define it as your homepage for the userrole that has just logged in.

(Note that you don't need to deeplink to a login form, the deeplink has its own login functionality, just disable the 'allow guests' property)