The Prophet ﷺ said that faith has some seventy branches, the highest being "lā ilāha illā Allāh" and the lowest being the removal of harm from the road (Sahih Muslim 35) — so clearing litter is an act of faith, and casually dropping it is its opposite. Allah forbids corrupting the earth after it has been set right (Quran 7:56), and He does not love those who spread corruption in the land (Quran 2:205). The Prophet ﷺ also warned his companions against sitting in the roadways, and when they said they needed to meet there, he told them to give the road its right: lowering the gaze, removing harm, returning greetings, and enjoining good and forbidding evil (agreed upon — Sahih al-Bukhari 2465, Sahih Muslim 2121). Vandalism, graffiti on others' property, blocking pavements and dumping waste all fall under harming people, which is forbidden whether those harmed are Muslims or not.
Q&A · Society & Ethics
Does Islam say anything about littering and keeping public spaces clean?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.