Hi,
You should not define a default value for the required fields.
(I made an improvement for the next HikaShop release to let users configure a required custom field without default value ; without displaying a warning message).
The best will be to use a placeholder instead of a default text if you want to do in the same way you are doing now. But it will require some modifications in the custom field system.
It could be an interesting idea for an improvement.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.