Destroying is the process of changing the way something is vibrating and thus fundamentally altering it and destroying the original vibration. Maintaining is the process of keeping something the way it is thus preserving the original vibration. Restoring is the process of changing the way something is to better match the way it used to be, or at least improving upon the original vibration which destroys the original vibration but leaves you with a more desirable vibration.
For example, imagining hitting someone with your car is akin to destroying. Appreciating someone as you drive by for the way they are is akin to maintaining. Imagining someone you drive by being as they used to be, or at least improving upon the way they are, is akin to restoring. All of the thoughts you think either destroy, maintain, or restore depending on the thoughts you choose to think. By choosing to think thoughts that match your desires, that which you are thinking about will ultimately be destroyed, maintained, or restored depending on the nature of your desires.