When you try removing the vSAN File Services config completely there is no easy option by today including vCenter 7.0.0b. Especially when you want to change the Network configuration (portgroup and IP addresses) you can´t do this from the UI.
After disabling and re enabling File Services on the UI the wizard will show you the old settings but wont let you reconfigure it. Basically it´s because the settings are already deployed with the vAPP that´s still there.
You need to remove the OVF Files that are sitting inside the vCenter Appliance.
- Login to vCenter via ssh using root
- rm /storage/updatemgr/vsan/fileService/ovf-188.8.131.520/*
- Reenable vSAN Fileservices in the UI and you can now start from scratch
Now it´s up to VMware to change this and getting a UI option for it.