Sometimes after you go through the act of casting a sigil you realize that you want to undo it. You can always go through the process of undoing a sigil once they have been activated. To begin the undoing process it is important to go through the act of cleansing, and banishing the kna of the sigil, which would at least release the spiritual kna from the sigil, and could even go through the act of lessening the imprint in your mind stopping at from continuing to manifest more things. Next destroy the representation of the sigil, if it is a passive one. This will release what spiritual kna it has left, and will allow it to have its last imprint in your mind instead of its continuous imprint.
One way that you can go about undoing a sigil is by allowing it to run its course. Which is pretty much just allowing the sigil to manifest what it can, and run out of kna, and it will slowly release the imprint in your subconscious mind. If you have a passive sigil, you should go through the act of destroying it, this will allow it to fully activate, so that it can eventually run its course nullifying itself. This method is not the best because it allows the kna of the sigil to continue on manifesting into reality.
Another thing you could do is another sigil to undo, and counteract the first sigil. In order to do this all you would have to do is create a sigil with the intention of stopping the first one, and then charge, and activate it like normal. This would send out spiritual kna to nullify the kna of the first sigil, and will also go through the process of overriding the imprint in your mind.
It is important to know the undoing process for a sigil if you are going to be using them, so that you are always able to stop a manifestation when you want to do so. You can even use these understandings to go through the process of undoing someone else’s sigil work, if you ever find yourself in need of doing so.