Tenant installs swimming pool without permission

[Ly Huynh]

I saw the tenant put the swimming pool like 3-4 feet high at the back yard without my permission. How do I tell them in the letter to remove it?  I did not check my insurance but I am sure they will not agree with it. thanks 
Tenant installs swimming pool without permission

[Nathan Gesner]

"Dear Tenant, I did not give you permission to add a pool. It will destroy the lawn and it may violate my insurance. You have 72 hours to remove the pool and repair any damage caused by it. I will be at the property on [DATE] at [TIME] to verify compliance."

If they don't comply, start the termination process.