BuddyPress.org

SOLVED:

actually this helped :

https://buddypress.org/forums/topic.php?id=2602&replies=2#post-14193

so..

there are 2 ways to delete users in the WP-AMIN :

one is for the hole BP and one is for the particular blog…

you should go in wp-admin > admin > users

not like me – wp-admin > users > authors & users