An animal can be undrafted from a draft (sort) list if you decide she does not need to be selected.
To undraft an animal from a draft list in the web app:
Click on Drafting then select the draft list you want to modify.
Next to the animal you want to remove, click Undraft.
This will remove the animal from the current draft list. You can optionally select future draft lists to make sure the animal is removed from those draft lists too.
To undraft an animal from a draft list in the mobile app:
Open the draft list you want to modify.
Next to the animal you want to undraft tap - .
This will remove the animal from the current draft list. You can optionally select future draft lists to make sure the animal is removed from those draft lists too.
