Just like you, I tried this feature in Ubuntu 16.04. I thought it was nice but didn't want to use google-drive that way... then I was mildly annoyed by the fact that not even removing my google account and changing the settings on Online Accounts worked. I couldn't find the Files switch.
So I found this workaround, I hope this helps somebody.
Locate the file:
and edit it. You'll see some blocks of text representing the same settings you could find on the Online Accounts menu shown by @nvelosa.
Find the flag
Files enabled=true under the desired google account and change it to
In my case I immediately saw nautilus file explorer hiding the shortcut and finding myself annoyed no more.