Movie Content on IOS and OS X Devices

I have multiple Apple devices on both coasts in two homes and an office. My two primary devices are a Mac Pro Cylinder with a 1TB solid state drive and a MacBook Pro with a similar 1 TB solid state die. I am using the latest versions of iTunes and OS X and IOS. I also have a late 2008 MacBook Pro with a 750 gb hard drive. I want to remove all of my purchased movies from this last device to free up disc space. When I try to delete a movie, I receive an error message stating that the movie will be removed from all devices. I have an iPad Air 2 with 128 ,b of storage and I want to retain the movies on this device so I can watch them off line when I fly coast to coast. How can I selectively delete movies on one device without it impacting the movie library on other devices? I also have two Apple TVs but those movies are streamed from the cloud.