Have a Membership at the YMCA of Greater Charlotte can I come there as well even on the Saturday mornings and Sunday morning

Yes

Yes, with your Y Membership, you can visit any branch within the greater Charlotte area. Most YMCA's within the greater Charlotte area are open both Saturday and Sunday. Both days will most likely have differing hours from their weekday hours, especially Sundays that don't typically open until noon and close around 5 or 6pm.

With a YMCA membership, you can come during all hours that the branch is open. On Sunday, most branches don't open until noon.