Is this person allowed to do this to me?

First of, I own a business with a little deli at the back. Around March, my mail lady wanted to rent out the kitchen so she did; they opened around April. Three days ago, she was furious at me because she wasn't making any money from her little deli so she said she wanted to stop her business. Then, I told her that she couldn't because she signed a contract that stated that she needed to fulfill her contract until October - it was a six months lease; however, I told her that she could stop her business but she would need to pay me for July and August (I wanted to give her a break.) So yesterday, I saw them taking all of her equipments out of my deli without my permission or notifying me. They didn't leave me any rent money and today, she was suppose to deliver my business mails but she didn't come to deliver. It seems like she is trying to avoid me. What types of action should I take? Thanks in advance