Oops, it doesn't look like 'decluttering day' is a national day..

Other days

lisp

Lisp Day
first love

First Love Day
buddy

Buddy Day
cuddle up

Cuddle Up Day
ponytail

Ponytail Day
cat girl

Cat Girl Day
bow tie

Bow Tie Day
my little pony

My Little Pony Day
promposal

Promposal Day
bonang

Bonang Day