You dont. Its most likely spam.

It appears to me, to be wallpaper too. Someone probably primed it and painted it. The texture you see is from the type of roller that was used.

Looks like that post has disappeared.

My guess too some kind of wall paper . My advice get rid of it you will hate that texture forever. There is wallpaper called anaglypta that has sometimes a apttern or just texture used a lot in places where old plaster walls are not in good shape . Where do you live ?It is possible the last owners just covered the drywall with that type of paper but no drywall material to cover the joints first.. If that is the case removing it will be impossible it will just tear off all the paper from the drywall when you try . Is this everywhere in the house ?

In an inconspicuous location, I'd use a putty knife or scraper or razor blade or even a small screwdriver to see if you can pull a bit of wall paper away from the wall.

My husband thinks it's the paper that goes on sheetrock with very little texture on it.