Do you mean the pipe with the ball valve in it that shuts off the flow of fresh water to the hot water tank..?
If thats what you're talking about, it helps when filling up your 150 gallons fresh water tanks, you don't have to fill the hot water tank before the water pump will immediately circulate fresh cold water when there is only a few gallons in the tank. Other wise, before the water pump will circulate water, the hot water tank must be filled by the pump first. This takes a good 5-10 minutes or so if you have a 10 gallon hot water tank.
I've used it before, but usually just let the rv water pump run when filling the tanks. I'm in no rush and with the hot water tank full, that gives me 160 gallons of fresh water. I also leave the hot faucet open to help bleed air out of the hot water tank while filling with pump on.
Don't think I'd remove it. Might be good to have it in some situations so as to be able to isolate the hot water tank.
Probably be harder to remove it then fix your leak..?
2007 WW FSW3200
RZRS k&t Turbo
2 LT500
1 Lt500 hybrid
F350 CC 6.7PS Platinum