I would my client can t see sites in "My sites" except

Hello,

I would my client can t see sites in "My sites" except the main site and his own site.

If not possible to allow the main site and his owm site, just allow his site.

I have tried with CSS to totally hide My Sites but without My sites it s more complicated to access the site and admin panel.
So just would like to remove others sites.

Someone see a solution?

Thank you

Ludovic