suse_register -a email=user@customer.com -a regcode-oes=9876543ACAB0

zypper ls
zypper removeservice nu_novell_com
rm -f /etc/SUSEConnect
rm -f /etc/zypp/services.d/*
rm -f /etc/zypp/credentials.d/*

SUSEConnect -r 9876543acab0 -e user@customer.com
SUSEConnect --status-text

zypper ls
zypper removeservice SUSE_Linux_Enterprise_Server_12_SP3_x86_64
SUSEConnect --de-register
SUSEConnect --cleanup
rm -f /etc/SUSEConnect
rm -f /etc/zypp/services.d/*
rm -rf /etc/zypp/credentials.d/*

https://support.microfocus.com/kb/doc.php?id=3303599