How to only show their subsite in admin toolbar/menu

Hello,

I built a sub-site for the BuddyPress community for all users. Then I noticed that any sub-site owner will be able to see 3 sites in their admin toolbar, one for their own site, one is the main site, one for the buddypress community site.

How to let sub-site owner only see their own site in the Admin toolbar and dash board? I don't want to confuse them and there is no need for them to access other site's dashboard rather than theirs.

Regards
YZ