2 whom it may concern: I managed my design as follow:
ucr set ox/ModuleAccessDefinitions/oxseforucs_webmail='webmail,publication,globaladdressbookdisabled'
Configured students with OX permission Webmail and I needed 2 set:
/opt/open-xchange/sbin/changeuser -c 10 -A <oxadminuser> -P $(< /etc/ox-secrets/context<contextnumber>.secret) -u <username> --access-global-address-book-disabled on
manually for all students, as the UCR seems not 2 work (i set it to be on the safe side). Also if I change the context and/or ox user details (2 trigger a new user sync) the address book was presented and filled. With the manually set the address book icon still was presented, but no entries anymore. In another test system the icon disappeared. Anyways the students do not have entries anymore.
U can not set access-global-address-book-disabled 2 on if the ox permissions are higher than webmail as the address book is mandatory for groupware.