It's an option in the settings (assuming you're using automatic1111 webui) but to make it easier, you can add it to the top of the UI by going into settings: User interface > and adding "CLIP_stop_at_last_layers" (without the quotes) to the Quicksettings list box and click apply settings.
You may need to restart the UI and after that, you'll see the Clip skip at the top of the UI window and can easily change it as desired. if you don't see it after the UI restart, you may need to fully restart. (Closing the terminal and relaunching it.)
If the interface is the same for colab version as it is for the local version, then these steps should also work for that,