To access the profile page for your account, click on the profile icon at the top right of the page. and click the Profile page link.
That will take you to your profile page. Changing your name and clicking 'Save Changes' updates your display name in the Graffle Management Dashboard
The My Companies tab shows you a list of all the companies you are a member of. There will be a 'Leave Company' button next to the companies in which you are a Member or Admin. Click the button to leave the company. Doing so will mean that company is no longer available in the Company Switch dropdown menu at the top right of the app.
The Invites table shows you a list of companies to which you have been invited but not yet Accepted or Rejected the invite.