Under the tab "MEMBERS" of your organization, you find a list of its members and their roles.
Adding new members
Click on the button "INVITE PEOPLE." A dialog will open and you be able to invite your colleagues by entering their email addresses.
On the right side of the member's list, you can set roles: "MEMBER" or "OWNER," whereas only owners can add new members and change roles.
Searching for a member
Use the search field on the top of the tab to locate the organization’s members by entering their names or email.
Removing a member
Also on the right side of the member's list, you will find a red "REMOVE" button beside each member—just click on it to remove a member from your organization.
Note: This account will be downgraded to a free account (or premium account, according to the specific subscription plan of the user).