He used a small pair of scissors to trim his 'mustache'.
The actor was wearing a false/fake 'mustache'.
a 'mustached' man [=a man who has a mustache]
(..) Guten Tag. Hello. Wie geht's? Wie geht's? Swine bird. That is my private mustache, you naughty bird. Schwein. No, no, no, wait. It's me, Inspector Clouseau of the Sureté. She's coming. Yes, (..)1975 The Return of the Pink Panther