DROPPING GAS TANK

I have the fill tube,and the strap bolts out.
The hard plastic tube that goes from the fumes can,to a "valve" on the frame, how do you disconnect it?
I look at the connection,and do not know how to get it to release.
The hard plastic tube that goes from the fumes can,to a "valve" on the frame, how do you disconnect it?
I look at the connection,and do not know how to get it to release.
