How to change the sub ip address to the main ip address under an interface?

Configure the sub ip address as main ip address, then the old main ip address is automatically substituted. For example: 185.79.175.198 is the sub ip address. Then change it as main ip address.
[Huawei-GigabitEthernet1/1/0]ip address 185.79.175.198 255.255.255.0 sub
[Huawei-GigabitEthernet1/1/0]display this
#
interface GigabitEthernet1/1/0
description ithis
undo shutdown
ip address 193.149.1.198 255.255.255.128
ip address 185.79.175.198 255.255.255.0 sub
dcn
#
return
[Huawei-GigabitEthernet1/1/0]
[Huawei-GigabitEthernet1/1/0]ip address 185.79.175.198 24
[Huawei-GigabitEthernet1/1/0]display this
#
interface GigabitEthernet1/1/0
description ithis
undo shutdown
ip address 185.79.175.198 255.255.255.0
dcn
#
return