Once you have created checklist template, you can still edit it.
From the main menu, click on Configuration > Templates > Checklists
Search for the checklist template you wish to edit
Click on edit to access the editor
Once you edited everything you wanted, click on save to apply your changes on next missions.
Edit checklists tasks
The tasks can't be edited, because this will comprise the historic data from past checklists. Tasks can be copied and deleted though, and the past data will be kept in the system.
Copy task you want to edit, then delete it.
Edit the task you just created.
Once you edited everything you wanted, click on save to apply your changes on next missions.
Deactivate a checklist template
To deactivate a checklist go to Configuration > Templates > Checklists
Click on Edit
Disable the checklist.
The checklist will still be visible in the checklist tab.
Delete a checklist template
You can delete a checklist by going to Configuration > Templates > Checklists
Click on the ... on the Action column and click on Remove
You will need to delete all the rules first before being able to delete the template.