You have defeated the voltage regulator by removing the tube. It is in parallel with the power supply, so the power supply will still supply voltage to the tubes. However you will find that the B+ at the inputs of the PC boards for the outer, preamp tubes is too high since the regulator is no longer controlling it. Running without it could require the C4S loads on the preamp tubes to dissipate too much excess voltage and they could run hot.
It also won't sound as good without the regulator.
