I will do what I should have done a long time ago.
4 seconds sound clip from the Santa Claus Is Comin' to Town (1970) movie soundboard.
You can hear this line at 00:34:18.861 in the Blu-ray version of the movie.
Quote context
[...]
- About face. Forward march. Hup, hup, hup, hup, hup, hup!
- Phew! Thank heaven there were no toys.
- And that's how he started leaving presents in stockings.
- I will do what I should have done a long time ago.
- I will set a trap for that bothersome Kringle. His next visit to Sombertown will be his last.
- But she was too late. Kris had already left with his toys.
- You must help me stop Kris. Please, use your magic.
[...]