I have tried using these steps and get the same responce
Sign in with your work account on dropbox.com. Click your team name at the bottom left of the page. Click Groups and members. Select the name of the group you'd like to add members to. Click "…" (ellipsis) beside the member's name, and choose Remove user.
Failer message at top of window is
"Failed to load modal"
I need to remove this user and all files/folders that got downloaded to their device.