If the singular of a word ends in an s-sound or its plural makes an extra s-sound, simply add an to form the plural. ies es s apostrophe s ('s)

If the noun is plural, just attach an apostrophe. If the noun ending in s is singular, most sources recommend adding both the apostrophe and an additional s. In these cases, the apostrophe + additional s adds another syllable to the pronunciation. If the extra syllable sounds unnatural, add just the apostrophe.

Explanation:

as for symbolic actions, the narrator's tearing down the wallpaper in an attempt to find the "woman" in the wallpaper represents her struggle to retain or regain her sanity.   the wallpaper has been part of her confinement and by her tearing it down, she is freeing herself from that confinement.