Checkbox Selection

I don't  understand the question properly  you want to  completely hide grid column or just the data part , If it's data then use if  in the "value" param or if it's column use "Show when". I wrote a sample code for hiding data in "fieldC" for your reference 

a!localVariables(
  local!X: {
    a!map(fieldA: "a", fieldB: "", fieldC: "XYZ"),
    a!map(fieldA: "b", fieldB: "", fieldC: "ABC"),
    a!map(fieldA: "c", fieldB: "", fieldC: "EFG")
  },
  {
    a!gridLayout(
      label: "Editable Grid",
      labelPosition: "ABOVE",
      headerCells: {
        a!gridLayoutHeaderCell(label: "Field A"),
        a!gridLayoutHeaderCell(label: "Field B"),
        a!gridLayoutHeaderCell(label: "Field C")
      },
      columnConfigs: {
        a!gridLayoutColumnConfig(),
        a!gridLayoutColumnConfig(),
        a!gridLayoutColumnConfig()
      },
      rows: {
        a!forEach(
          items: local!X,
          expression: a!gridRowLayout(
            contents: {
              a!textField(
                value: fv!item.fieldA,
                saveInto: fv!item.fieldA,
                readOnly: true
              ),
              a!checkboxField(
                choiceLabels: {""},
                choiceValues: {true},
                value: fv!item.fieldB,
                saveInto: fv!item.fieldB,
                
              ),
              a!textField(
                value:if(fv!item.fieldB ,fv!item.fieldC,""),
                saveInto: fv!item.fieldC,
                readOnly: true,
                
              ),
              
            }
          )
        )
      },
      selectionSaveInto: {},
      validations: {},
      shadeAlternateRows: true
    )
  }
)