Can I manually edit oxide groups file? I tried few editors but can't find good one. Don't really want to use command in console as I do have to many users to check/remove and in editor would be much easier and faster to sort out groups.  

Editing it manually is not supported, but the file type is Protobuf which there are a few editors out there for.

Wulf, thanks
if i remove all group to remove all users and create some group again will it have same perms as before removing or would I need set all perms again?

You'd have to grant all of the permissions again as you would have deleted them with the groups.