Admins & Managers can invite, edit and remove users. You'll find the user page in the top right hand menu.

There are 2 options when adding a new user:
Invite User - user will receive an invitation email and set their own password. Useful in most cases
Set password - set a password when creating the user, who will not receive an invitation. Useful for setting up users before they are ready to start using Trail.
Invite User
To invite a new user to join your company, select the ‘Invite User’ button, enter the user’s details and set responsibilities (note - it could land in their Spam inbox!)
Enter details:

Set responsibilities:

Team members must be assigned to a single site
Managers can be assigned to any combination of sites or groups
Admins have access to the entire organisation
More on roles and permissions.
When you’re happy, select ‘Send Invite’ and the new user will be sent a 'Welcome to Trail' email with instructions to create a password and log in to their account.
---
New User
To set up new users without sending out email invites choose ‘Set password’
This is useful if you want to set up a few Trail accounts before giving out access at another time, or if you want to manage passwords for everyone.

If you’ve set up the account as a Manager or Team member, you’ll need to assign a Site or Area.
You'll then need to send passwords and instructions to login at http://web.trailapp.com
---
Editing user access
Go to the users tab and select the user you want to edit
Change the role of access from the drop down lists

---
Removing users
If you ever need to delete a user from your account, find the user in your list of users and simply select the small red dustbin icon to the right of their name.

You’ll be asked to confirm and then the user will no longer have access to Trail.