Re: How to remove those brackets ?
IMHO, murder is a sin. This is a little further down the scale.
Use a custom language file to get rid of these numbers in parentheses. https://codex.buddypress.org/how-to-guides/customizing-labels-messages-and-urls/ Look for entries like
Groups <span>(%d)</span> and replace them with
Groups. Eventually it would be nice to get this markup out of the core and into a template file, but in the meantime this will do the trick just fine.