Cooking Tenants - Grease Problems?

[Max Schroeder]

I own a strip mall right outside of Chicago, and have been renting out to 3 different restaurants within the strip.  This is my first property, and time renting to cooking tenants.  My first time getting up on the roof since they've begun renting, and there's greases and fats all over the place. It smells and looks horrible. Not to mention i'm noticing rips in the roof.  Could they be caused by this grease?

I've never dealt with this before, and really don't know what to do! Any help or suggestions would be great!