The "Remove from Group" command is what you might remember from the native FileWave admin as "Delete", and it has the same consequences. But, in the native admin Delete was the same for the original object and the copies, even though the result was different. The WebAdmin has split this into two commands to help clarify.
We'll use this command whenever we want to remove a copy of a device from a manual group. There are no consequences to data in FileWave, and any other copies will be unchanged. Note that if this copy had payload content assigned it via a deployment that it would lose that payload.
Highlight any device copy (in a manual group), from the (...) button, choose "Remove from Group":