that is a ground wire and ya should leave it.now couple of ? 4 ya
1]were ya got that wire attached to
2]weres the antenna mounted
3]is this a single or co-phased set up
4]if co-phased is your coax 75 ohm coax
5]what lenth of coax ya using for antennas,jumpers
6]what kind of vehicle ya mounting this to
7]are ya using a external swr meter
need ALOT more info please