Installing a new Lowe's Whirlpool 40gallon Gas water heater.
Small leaks at the cold input hose receptacle at top of tank.

This water heater has 3/4" plastic female receptacle at top of tank.
We use new Watts stainless steel 3/4" MIP to the receptacle (hose by Watts at Home Depot - other end 3/4" FIP 18" length).

When I try to remove this cold water connecting hose, it just turn and turn and will not come out.
What can I do? Thank you.