"Not A Lawyer" speaking !! - Looked up citation in New Castle County Code - This was passed 5-26-98, apparently. As I recall , there was a Delaware law passed (effective) 7-4-85 that counties and municipalities could not enact their own firearms statutes (to keep things consistent throughout the state). So a '98 NCC statute would be contrary to the '85 state law.
See: De. Code Tile 9, Chap.3, Sec.330 (c) and (d).--- for Counties, and
Del. Code Title 22, Chap. 1, ,Sec. 111 for Municipalities.
DE law was amended, signed by Gov. Markell, 8-17-15. Newark has already amended it's statutes for municipal buildings (which is what prompted the change, because someone was OC'ing to Town Meetings, and it scared other residents). However, a story in Newark Post (maybe 6 months ago) was headlined something like " Newark to reverse Illegal Gun Ban" regarding OC'ing in City parks.
Don't know if Glasgow Park is Municipal, County, or State Park - never been there.