ENACTMENT: Try to imagine away your intuition of three-dimensional space. Trying to do so only reinstates that intuition.
Imagining away the formal intuition of space can only be enacted by imagining it (again). On first glance, this is no different from the Thought Suppression Paradox— the act of trying to negate a presentation (concept or image) necessarily calls it to mind since it is the object of an articulated command.
But it is actually slightly different. Space arises as a presentation under all propositional attitudes. It is the a priori outward orientation of outer sense that makes its negation impossible. Outwardly imagining anything, including the attempt to think away the form of outer sense, activates and amplifies consciousness of it:
We can never have a presentation of there being no space, even though we are quite able to think of there being no objects encountered in it. Hence space must be regarded as the condition for the possibility of appearances, and not as a determination dependent on them. Space is an a priori presentation that necessarily underlies outer appearances. [A24/B38]