At least part of the problem might be that you don’t seem to have a good understanding of the wireless communication protocols used by the ST hub.
Hue bulbs use Zigbee, not WiFi, to communicate wirelessly.
Here is an article that describes a few wireless protocols used by iot devices. ST supports z-wave and zigbee for direct pairing of devices to the hub. Other devices can work with ST but they go through your LAN or the cloud.
There’s also a lot of information on the ST support website about products that are certified to work with ST.
This is the comprehensive list of certified devices (in the US at least, UK is different).
And here is the support page for hue bulbs, which includes very detailed instructions for adding and removing. However you’ll notice that the official integration with ST makes use of the hue bridge, the bulbs don’t pair directly to the ST hub.
https://support.smartthings.com/hc/en-us/articles/200848024-How-to-connect-Philips-Hue-devices
Since you apparently added your bulbs directly to the ST hub, you may need to take extra steps to remove them.
Edit: and as @jhamstead pointed out (posted while I was composing my post 
), it might be difficult/impossible to do so.