This is a pulse shaping circuit, that has three amplifiers: U1, U2, and U3. The shaping amplifier is the 8pin component far right. Both U1 and U2 serve as "coarse gain," which are activated by the switch in the bottom left of the diagram. U3 controls the polarity of the input signal, and is also activated by the switch in bottom left. I would like to remove U3 as I have no need for polarity switching.
U3 is connected to another switch, U7, which is boxed in blue along with U3. My first thought is to simply bypass the blue-outlined portion of the circuit. I would do this by connecting the output of U2 to the R7 and shaping amp input, both boxed in black. I imagine this is not the "proper" way, and would require a few components to properly deliver the output of U2 to the shaping amp input.