We are taught and automatically born into a system that turn us into "financial slaves" or "financial soldiers" of the system.  

It was clear to both parties, with email exchanges confirming that the end date is July 15th and that there will not be renewal of lease.However, I forgot to stop the automatic rent collection through Zillow, resulting in the tenant paying the full July rent on July 10th, which has already been transferred to my bank account.

Set it up on a system like apartments.com that automatically collects the rent for you and find a good handyman that can help when you need it, which will not be often.

When I followed up and asked for a specific reason (thinking it might require an additional payment towards principle to put me under the threshold) they wrote back informing me that investment properties do not qualify for automatic termination and that PMI will remain for the life of the loan and if I want to remove it I can look into refinancing. 

Would we be automatically classified as real estate dealers in the eyes of the IRS for this one flip?

It was clear to both parties, with email exchanges confirming that the end date is July 15th and lease won't be renewed.However, I forgot to stop the automatic rent collection through Zillow, resulting in the tenant paying the full July rent on July 10th, which has already been transferred to my bank account.

This is to protect yourself so that if a second offense occurs you can automatically move to evict should you choose to.

Then you can get it automatically set up so that you will get the  property back without having to go through a And don't beat up on yourself because this deal didn't work perfectly. 

Most PMC software is set up for electronic rent payments by tenants that automatically updates rent ledgers. 

., if they’re not automatically updating you.