Unfortunately, that can not be achieved through a control condition.
However, that can be easily achievable through the checkbox's property. As you may know:
- checkbox = checked ==> checkbox's property has a default value
- checkbox = unchecked ==> checkbox's property does not have a value (is empty)
with that being said, in order to uncheck a checkbox based on a condition, you can use a "Set installer property" control event, as it follows:
Event: Set installer property value
Property: CHECKBOX_1_PROP (or the name of your property, if you have changed it)
Argument: {}
Condition: your_condition
This way, if the condition is evaluated as true, the checkbox's property will be set to empty value, therefore unchecking the checkbox.