Updated Feb 22, 2013
You change the designation / status of yourself or anyone you have already shared a trip with to or from a traveler / planner / viewer or remove them completely.
To change the traveler's status to or from traveler / planner / viewer:
1. Sign-in to your account on www.tripit.com.
2. Open the itinerary of the trip by clicking on the trip title on the Trips page.
3. Click on arrow to the right of the name of the person whose designation you wish to change and then select the new designation (Traveler, Viewer, or Planner) by clicking on that designator.
That's it. You're done!
To remove a traveler / planner / viewer from the trip:
1.) Click on the Remove from trip button below the person's designation.