It has two situations:

1. For a physical port, no configuration is performed before the Eth-Trunk is added. After ntdp enable is configured, ntdp enable is displayed for buildrun. If undo ntdp enable is configured, undo ntdp enable is displayed. See the following information:

interface GigabitEthernet0/0/9
#
interface GigabitEthernet0/0/9
ntdp enable
#
interface GigabitEthernet0/0/9
undo ntdp enable
#
The cause is that there are three states (not configured, enabled, disabled) for the NDP/ NTDP in the V100R005 version. Therefore, if the enabled or disabled state is configured, the value of buildrun is written.
2. After the physical port is added to the Eth-Trunk1, the NDP/NTDP configuration cannot be deleted. See the following information:

interface GigabitEthernet0/0/9

eth-trunk 1
undo ntdp enable
undo ndp enable

The cause is that the physical port can be added to the Eth-Trunk1 only after the NDP/ NTDP is disabled, and after the addition the NDP/NTDP cannot be enabled.