You can also use the scale feature.
- Create a cylinder
- Select the scale feature
- Pick the top cylinder face
- On mac,press the option key, and on Windows, press the ctrl key, to show the marker for face center and enable uniform scale option
- While the key from #4 ( option, on mac, and crtl, on Windows) is pressed, select a grip along the diagonal and move it towards the center marker to get a truncated cone.