Do you want to remove floor-to-top bookshelf structure or a few shelves here and there?

Beautiful built ins. I would wall paper the back of the shelves

Playing with the idea of painting the backs black!

I would like to remove a few shelves here and there. Thinking about the 2nd and the 3rd.

Might depend on the height of items you have to go in the openings. A good "rule of thumb" is 1/3 books, 1/3 large decor items, 1/3 open space. Don't decorate with anything so small that it requires a trip across the room to identify the object.

That's a great tip! Do you think what I have currently would look too small for the openings?

Here I've marked too tall and too short or unable to be identified items. Books that reach to the shelf above them I consider too tall. However, laying them on their sides or doing shorter stacks of them to serve as stands for other items may work for you. Photos can't really be seen from across the room and I prefer them to sit on tables nearer the seating so they can be viewed. With a relocation of the shelves to different heights, some of your items will still do fine.

Removing what looks like fixed shelves is not going to be easy or pretty. And it may be more work than you are bargaining for.

Use an oscillating multi tool to cut the shelves off flush with the sides. The shelves could be set in dadoes, glued & maybe nailed. Or they may just be end nailed & no dado.

If dadoed, you will need to very precisely cut some thin panels to attach to the sides to cover the mess. Hopefully the center upright divider is not flush with the gable end of the shelf unit so the raw edge of the new panel is hidden behind a face frame.

You will also have to deal with the horizontal stripe on the wall or shelf backing that will be exposed when the shelf is removed. There may be nails or staples if the unit has a back and a ridge of paint. Pull any fasteners out, sand the paint ridge, fill holes, sand, prime, paint. Filling the holes likely will require 2 steps. Fill, sand, touch up fill, sand.

I will be the bad guy IMO I see nothing on those shelves that screams display me I need to see where this area is in the space IMO all the shelves should go and some art added above the bases but I hate eye clutter .I assume you do not want a bigger TV if that is not so then please share that info too. Post pics of the whole room then we get a clue as to your style.

I can understand your desire for wanting to remove a few shelves, but they look fixed in place. If they are, cutting them out is going to mess up the rest of the shelving. A pro might be able to do it and have it all look perfectly seamless, but I don’t know. Regardless, I personally think you have too much stuff on your shelves. Pare way back to quiet it all down. I’d try that first before I start sawing out shelves.

I think shelves are to store books and things you love. Go ahead and fill them up!

I really appreciate the helpful comments! I will definitely be leaving this up to the pros.