Replace the (resource.name = "Sheet1") with (resource.name != "<SheetID>")
Note: you can get the sheet ID from the the single configuration tab in the DEV-HUB
Replace the(user.name = "user1") with (user.name = "<UserID>")
This will actually restrict a user from viewing a particular sheet
Yes you can add sheet security.
What you want to do is create a rule that grants read access to a sheet where the name = your_sheet_name and user.roles="RootAdmin"
I would be reluctant to implement sheet security as I think it would require constant maintenance as your environment changes and/or sheet names change. I also think people may be reluctant to answer and give you an exact rule as everyone's environments have different security rules implemented.
Something like this may work. You just have to experiment a little. In this example, it grants read access to the Performance Figures sheet only if your role is RootAdmin.
Hope this helps.
I do have another login that I am using for testing and that user can still see the sheet. Ant other thoughts? Have you been able to get this to work?
N27 W23957 Paul Road, Suite 100, Pewaukee, WI 53072