How do I remove the back of this chair? TIA

Probably have to lever it out unless access is from the back!

There should be screws holding the back in place.If you can't see any, they are probably located under the back layer of fabric, remove that (cut away) and you should see them.

https://www.youtube.com/watch?v=I4eU2saxQSE

There are usually screws attaching it to the frame.

here are ideas

https://www.youtube.com/watch?v=QMAI3rgqV8M

I agree with Redcatcec!. Probably four brackets holding the back. Two on top on each side of the handhole and two on each side of the bottom. You might be able to feel them by pressing hard with you fingers along the back.

Hi Lenore, if you run your finger over the back of the backrest you should be able to feel the screws. If you can't feel any screw see if you can push the back out by placing a butter knife between the cushion and the metal frame.

There should be something holding the frame in place (usually screws) that needs to be backed out or loosened.

Hi Lenore: It looks, to me, like there are screws holding the back to the seat. If you remove these screws, the back should slide out. I'm thinking that the pressure of the tubing on the back is keeping the back in place. When you replace the tubing, the pressure should hold the back in place. There may be additional small screws on the inside bottom of the back to hold it up. Just MHO :)