You have to enter Studio, select de field you want to show/hide depending on the value of the other and select on the left column: Properties->Invisible-> and then create the rule when you want the field is INVISIBLE.

In the example: field with variable visibility: 'Variable data'

1. Insert the field
2. Define the Conditional rule in the Invisible 
3. Rule: Company mast be not set

In case you are in a record in winch the rule makes to hide the field, that will desapear, so you have to put it visible in order to work with in View->Show invible elements.

I hope this is useful for you.