Ah yeah, the example above was about to remove language selection and client links. To remove the social buttons you have to comment out the “<p class="social-button">” section (last section) in “/path/to/nextcloud/settings/templates/settings.development.notice.php”.
This is not possible in the mentioned personal.php, as it is included in the versions box and includes the social buttons from there. If you also don’t need the “Developed by the Nextcloud community, the source code is licensed under the AGPL.” text beneath the version information you could also comment out “<p><?php include('settings.development.notice.php'); ?></p>” at the bottom of the personal.php which includes developer info/links as well es social buttons. But if you ask me, it is fair and maybe also part of user license to give every cloud user the hint to the nextcloud developers there ;).