Ap, either you need enhanced isolation or not. If you need it, then you must also use a special relay, which provides this. Such a special relay provides enhanced isolation distances between the coil drive terminals and the switch contacts. The according terminals are widely separated. Then, you can let stop the ground plane under the coil drive terminals (including them) and leave the switch contacts free.

But simply to remove the solid ground plane makes no sense at all, because the terminals of your relay are still in close distance and the enhanced isolation is lost anyway.

Kai