SNAP: Simply snap off the nozzle/tip (it might look strong, but it has a weak point designed to be snapped off)
RESEAL: Spin the nozzle around to reseal. For a tight seal, press on a hard surface.
She’s quite full: So, before you open, tap the folded side of the tube a few quick times on a bench to move the gel down.
For a tight seal: give it a push on a hard surface before you throw her back into your travel bag.