/var/lib/dpkg/info/tftpd-hpa.postrm try deluser 'nobody'. Change username in /etc/default/tftpd-hpa from 'nobody' to 'foo' and repeat install/purge.
/var/lib/ dpkg/info/ tftpd-hpa. postrm try deluser 'nobody'. tftpd-hpa from 'nobody' to 'foo' and repeat install/purge.
Change username in /etc/default/