If a circuit from a voltage source has a potentiometer to ground, does voltage increase or decrease when resistance does?
R722 and VR722 appear to be the lower elements of a potential divider consisting of the undesignated resistor chain (1) on the right of the transformer. Lowering the resistance of VR722 will reduce the voltage at (2). (Think of the extreme conditions: if you reduce R722/VR722 to zero the output would be 0 V; if you open-circuit VR722 - making it infinite resistance - you will get Hv volts out.)

Be aware though that usually reducing the feedback voltage like this will increase the output voltage as the regulator will increase the output in an effort to get the feedback voltage up to its internal reference voltage value.