Unknown devices may those connected to your router which do not have a name assigned to them.
What do you mean by “unused” devices? The router retains the assigned IP address for some hours since it last connected.
Care to share a screenshot of the issue?
Sorry I probably didn't explain very well. There are devices that belong to other people listed and
I would like to remove them. Its been weeks since they have used my wifi.
On my home network. They shows as inactive. Not hurting anything I just want to delete them
and there is no option to do so.