What Grim said.
The valve is what is known as a three way. It has three ports, two of which switch between a third, common port. The common port is connected to the FPR. The valve therefore can be in one of two states at any given time:
1) FPR port and manifold port connected.
2) FPR port and atmospheric (filter) port connected.
Three ways valves are used anytime a volume must be equalized. In this case it's needed to equalize he line going to the FPR to atmospheric pressure. Without a port to the atmosphere the vacuum in the line to the FPR would be "trapped" when the valve cuts off the connection to the manifold. Make sense?
The TCCS makes the valve active during a hot start. It knows when the engine is hot by sampling the coolant sensor. When it does this the FPR control port is opened to atmospheric pressure with the result being the fuel pressure is increased. The entire point of this is to purge any vapor that may be in the fuel system. The ECU reconnects the FPR to the intake manifold a minute or two after engine start.
Since the fuel systems' "rest" pressure after the engine is shut down normally prevents vapor formation, removing the valve will likely be no big deal. However, if you should lose rest pressure or if the fuel system remains heat soaked after rest pressure natually bleeds off you'll have hard starting when hot. Think of the Fuel Pressure Up system as a back up of sorts to rest pressure.
I don't recall if the valve is a normally closed three way or a normally open three way. The difference would be in which port is connected to common when no power is applied to the coil. Perhaps someone else will chime in.
Probably more than you wanted to know. To answer your question, if you don't want to use the valve connect the lines together or run a new one. If you leave the hose missing your fuel pressure will not track manifold vacuum and will be high at all times.
