If the photos are downloaded to whatever device you are using, you should just be able to click on the camera icon and then select the photo you want to include. You might need to resize and many find including them under the comments is easier than including in the initial post.

Shrubs grow as large as they are genetically programmed, so terms like "trim back to size" and "overgrown" generally refer primarily to the siting - too big for that location :-) But many kinds of shrubs can grow that large or larger in 20 years.

It's a yew, Taxus species. This plant is immensely prunable and you can cut it back as hard as you like. One of the few shrubs/trees that really require no previous pruning skills at all :-)

I'm glad no skill is required to cut it back because I'm pretty sure I have no skill in this area ;-) I say that because I trimmed the tops off our hedges today and they don't look remotely flat. (They have no leaves just yet but should start budding soon given the current and predicted temperatures.) I've watched some landscaping videos and the pros seem to have no trouble at all squaring off hedges so that they are as flat as tables. I am baffled by how they accomplish this.

I have an (electric) hedge trimmer so I assume that is the proper tool to use on our yew but I'm not sure HOW to trim it. I'm inclined to cut it off at about chest height and make it as flat as I can and maybe trim the sides back some as well. The yew's natural shape seems to be round but I'd be open to other shapes as well. However, given how bad I am at flat, I'm not sure square is even in my wheelhouse, let alone round.

It's clear in looking at the bush that if I cut the side back more than a foot, there will be no green left, only branches. How long will it take to turn green again?

The yew appears all alone away from the house with no bush friends to hang with or to rub against. How do we even know this lonely yew out there on the Canadian prairie is over grown? What is it over grown in comparison to? Are you just assuming as a regular homeowner that the bush must be pruned because that is what you do to bushes?

Check out the shapes this man makes with his bushes for some inspiration - if you must prune the yew. Pearl Fryar Garden

Why not prune it to be more open instead of trying to restrict its growth. A more open natural look will be more graceful and less work in the long run.

A thinner appearance making the branching visible would not be an enhancement - look at the close up shots. The appeal and value of this specimen is its density and fullness. As is often the case with evergreen landscape shrubs.

The looser look I am talking about is more like the top that has not been sheared rather than the bottom which has been trimmed back probably for ease of mowing. There is nothing around it, why does it need to be small or shorter?

"There is nothing around it, why does it need to be small or shorter?"

Because the OP has explained that at 10-12' high and 8' wide, the shrub is too large in its current situation. How to reduce the size is the purpose of the thread.

Each of you have raised some valid points so let me address the ones that jump out at me.

You are correct in saying that the yew isn't bumping up against anything else. It has its own spot in the yard and would have to grow substantially bigger before it brushes up against the fence at the side of the yard or the small garden at the back of the house. The bush was planted in 2000 by my mother, who passed away 4 years ago. It was planted to commemorate the Millenium.

Maybe you're right and I should simply leave it alone. I just assumed that all plants should be trimmed back occasionally but maybe this is an exception. I know very little about trees, plants, landscaping etc. I find that this bush is starting to block our view out the back windows of the house so I thought it might be wise to trim it back some.

Is the occasional pruning - I think it's very possible this bush has never been pruned or trimmed - good for a plant like this? Or is it better to leave it alone?

By the way, we're a long way from the prairie in Southern Ontario. The prairie starts once your west of the western tip of Lake Superior. We're not too far north of Cleveland and Buffalo ;-) Lots of rolling hills and trees in this area, unlike the flat - and frigid in winter - Prairies.

We know nothing about the yew's current situation. It is too large in comparison to what? Perhaps the yew could be allowed to be a tree.

Now we know more about the yew which is a good. A picture that shows it in the larger landscape would be even better.

I drove from Detroit to Buffalo once through Canada. I didn't see much in the way of forest or hills until I got close to Toronto to turn south again for Buffalo. The longest part of the drive above the Lake, the land was flat as a pancake and lots of pasture. And no Trash at all lining the highway. Bravo Canada!

There is no gardening rule that states you must prune the yew.