I try to click the box to remove members but it does nothing.
Are you an admin of the workspace?
If not, you may not remove members.
If you are
1: Make sure you are following the guidelines here
2: Try accessing Trello through an Incognito/Private session (if using the web browser) or clearing your browser/application's cache
3: If all else fails, there could be a bug. Try contacting Atlassian directly.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.