Hello Bob, and welcome to Seven Forums.
The long s-1- number is the unique ID number of an user. These would normally be from users that have been deleted or not currently connected on the network.
If you are logged into an administrator account, then you should be able to take ownership of and set permissions to "Allow" your account "Full control" of the files/folders. You might see if using the "Take Ownship" context menu item below may be able to help.
Take Ownership Shortcut
If not, then see if using OPTION THREE in the tutorial below may.
Take Ownership of file - Vista Forums
Once you have ownership and access, you can safely edit
(delete) only the s-1-
numbers from permissions if you like.
Hope this helps for now,