Is there a way to unlink insync from my old pc?

I lent my pc with my insync account and I want to know if I can remotely sing out my account in that pc.

We currently do not have an option to do this for now.

But you can sign into your Google account that was being used and remove permissions for Insync to use that account on that instance of Insync for that computer.

In section “Apps with access to your account” I can remove Insync’s access to my Google Account, but not permissions of a given instance of Insync for a given computer

So looks like you may need to just remove the permission for all clients and them login to each individually.