Signals Notebook allows setting experiment elements as 'Mandatory' in an experiment template. Users can not delete/trash mandatory elements from the experiments created with that template.
Steps:
1. Log into Signals Notebook as an administrator
2. Navigate Signals Configuration > System Objects > Experiment > Templates
3. Open the experiment template you wish to modify
4. Select the element to set as 'Mandatory'
5. On the top right corner of the element look for a trashcan icon with and 'X' and click on it
6. The change will be saved automatically