|From Microsoft's Support pages:|
Homegroups can't be deleted, but you can make one go away by having all the PCs that belong to it leave. Here's how to leave a homegroup:
Open HomeGroup by swiping in from the right edge of the screen, tapping Settings (or if you're using a mouse, pointing to the top-right corner of the screen, moving the mouse pointer down, then clicking Settings), tapping or clicking Change PC settings, then tapping or clicking HomeGroup.
Tap or click Leave.