Motivated by substantive concerns with the limitations and negative effects of technology, this paper inquires into the negation of technology as an explicit and intentional aspect of design research within HCI. Building on theory from areas including philosophy and design theory, this paper articulates a theoretical framework for conceptualizing the intentional negation of technology (i.e., the undesign of technology), ranging from the inhibition of particular uses of technology to the total erasure or foreclosure of technology. The framework is then expanded upon to articulate additional areas of undesigning, including self-inhibition, exclusion, removal, replacement, restoration, and safeguarding. In conclusion a scheme is offered for addressing questions concerning the disciplinary scope of undesign in the context of HCI, along with suggestions for ways that undesigning may be more strongly incorporated within HCI research.