Delete Activity ONLY super admins and writer/author of activity

Hi all, I basicly am changing the Buddypress Activity Stream Page, putting somwhere else the "Delete" link. I have a great code which works but I only want it to be viewable for logged in super admins and the writer/author of the activity. And with Super admins which I've already used here, it works... but I can't get it to work for the author, that he/she can delete his/her activity. Can someone help me out? I REALLY appreciate it!

I've been looking for this for hours and hours but it just doesn't get working somehow.

My code so far:
<?php if ( is_user_logged_in() && is_super_admin() ) : ?>
<?php bp_activity_delete_link() ?>
<?php endif;?>