If you purchased the SketchBook desktop app from the Mac App store:
1. Click the Launchpad icon in the Dock.
2. Hold down an app’s icon until all the icons begin to jiggle, then click an app’s delete button .
Later, if you decide you want to use the app again, you can reinstall from the Mac App Store.
If you downloaded the Mac installer from www.sketchbook.com, you can uninstall by dragging the SketchBook folder into the Trash or right-mouse click and select 'Move to Trash'.
Go > Applications > Autodesk > SketchBook (folder)
To uninstall the SketchBook desktop app:
2. Under View by: select Large Icons, and then tap or click Programs and features.
3. Tap or click on Autodesk SketchBook, and then tap or click Uninstall.
4. Follow the instructions on the screen.