Don't show Delete Account in Edit Member toolbar dropdown if Settings is disabled

When Settings is turned off, there's no way to delete users through the front-
end interface, and the link 404s.

Fixes #5066

Props imath

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7233 cdf35c40-ae34-48e0-9cc9-0c9da1808c22