How to prevent one of the options in configuration option to appear in the purchase page

[pikerr]

Dear Team,

Due to our products in Japan is sold out, how do i prevent the clients from purchase the products in Japan?

My setting as follow

Products/Services set as regional ( US, Europe, Asia, Australia), I have created countries as Configuration Options. 

For example in Asia, configuration option (Location) will be Japan, Hong Kong, Korea, Singapore 

I have created 2 different sets of Configuration options for testing. 

First Option Group

Korea, Japan, Hong Kong, Singapore

Second Option Group 

Korea, Singapore, Hong Kong.

In order to prevent clients from buying Japan products, I have to choose Second Option Group , in this manner, Japan does not appear in the purchase location.

However for our monthly invoice generated for our existing Sendai clients, the location field does not show Japan, invoice not created.

the above method is suggested when i raise ticket to WHMCS Support.

Many thanks in advance for your valuable advise.

Pikerr