He spent a long time cutting all the waste paper into pieces.

Solution (By Examveda Team)

One word substitute is Shredding.

Slashing: vigorously incisive or effective.
Ripping: splendid; excellent.
Shredding: a piece cut or torn off, especially in a narrow strip. a bit; scrap.
Disposing: get rid of by throwing away or giving or selling to someone else.