From the welcome screen

1. Open Rotato
2. In the welcome screen, go to Templates
3. In the top right corner, click Options, then Manage Templates
4. A Finder window opens. Delete the templates you want to uninstall.

The welcome screen is available in macOS 11.0+

From the app menu

1. Open Rotato
2. In File → New From Template, choose Manage Templates
3. A Finder window opens. Delete the templates you want to uninstall.

From Finder

1. In Finder, go to ~/Documents
2. Delete the templates you want to uninstall.