How to "trim" bodies in an assembly in Solidworks?

I don't think there is anything that easy in the assembly level but here are 2 different ways I would do it instead of opening every part and finding the sketch etc...

  1. Step 1:

    OPTION 1

    Right click the part you want to change and click "Edit Part"

  2. Step 2:

    This will let you edit the part while you are in the assembly.. (Makes everything else transparent)

  3. Step 3:

    Select a suitable face, and create a sketch on it

  4. Step 4:

    Select "Convert Entities" from the ribbon or Tools>Sketch Tools from the menu bar. Then Select the inner diameter of the green Cylinder, and click the green check.

  5. Step 5:

    It will project that circle to your selected face in that part, click OK.

  6. Step 6:

    Do an extruded cut and select the region between your newly created circle and the purple cylinders outer diameter. Select "Through All" instead of "Blind" and accept.

  7. Step 7:

    Return to your assembly and the purple cylinders O.D. now matches the green cylinders I.D.

  8. Step 8:

    OPTION 2

    Right click the feature you want to change and click "Edit Sketch"

  9. Step 9:

    Alter the value to the desired size. (1.625 to 1.500 in this case)

  10. Step 10:

    Click OK, exit the sketch and return to the assembly.

    Hope this helps!