We're sorry for the trouble this may have caused you — let's see what's going on.
Try unlinking your Syska Smart Home account using these steps:
If you'll get the same results, try reinstalling your Google Home app. Make sure your phone, Google Home and Syska Smart Home devices are connected to the same network and within 15-20 feet of your router. Once done, try saying "OK Google, sync my devices".
Let us know how it goes.