Identifying & Pruning a Holly Shrub That Has Tree-Like Aspirations
Last weekend, I struggled to place a two-story ladder against my house and trim the top 3 feet of my big holly. Fully extended, the ladder is heavy and difficult to reposition, especially with a sharp-needled holly beneath it. To support the ladder on the sloping ground, I placed two 2x6s underneath one of the legs, which wasn't exactly textbook safe, but it was the best of several bad options. I then climbed up the ladder, with my alarmed wife providing a running commentary on ladder safety. Because my electric extension hedge trimmer is heavy, especially with arms outstretched, I had to release my grip of the ladder, hold the trimmer in both hands, turn sideways on one of the ladder rungs, and begin cutting, which involves much reaching and not a little flexing of the fully-extended ladder. Once I completed my work and descended, I had to promise my wife I'd never do this again. Objectively, it's a miracle I didn't fall off the ladder into the needle-like holly--with sharp trimmers in hand. A friend did something like this two years ago, while cleaning gutters, and ended up in Shock Trauma in Baltimore.
We cannot identify the type of holly from the photo.
The best strategy would be to remove and replace the holly with a plant that matches the site location and conditions. Plan for mature height and width of the new plant.
In general hollies tolerate pruning but generally no more than 1/3rd of the shrub at a time. More than that could weaken the plant and be susceptible to winter injury. Any severe pruning should be done in early spring.
Topping is not recommended and the plant would not look aesthetically pleasing. Consider that the plant is in a prominent location in your landscape.