Hi,
The easier to to look at the URL.
When you click on the category that you want to move (but you can't edit), you will see in the url a parameter called "filter_id".
Then, edit any category and replace the value of the parameter "cid" by the value of the "filter_id".
You will edit the wanted category and you will be able to change his parent category.
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.