Hi @Taylor_Flood, welcome to the Asana Community Forum 
Currently, it is not possible to edit/delete Rules created by another user. This is a popular request in the Forum, however! We do have an existing thread in the #productfeedback category for this request so I’ve gone ahead and merged your post with this to consolidate feedback! 
Regarding your specific case, when you deprovision someone who has Rules, their Rule will be paused and ownership of any Rules on projects will be passed to the Project Owner. If there is no Project Owner, ownership will be passed to the Admin who deprovisioned the user. Only the new owner of a Rule can re-activate the Rule to have it continue running. You can find more on Rules in our Help Guide: Using Rules in Asana | Product Guide • Asana Product Guide
If you need additional assistance, I would suggest reaching out to our Support Team: How to contact our Support Team ✉
I hope this helps!