Standard actions are managed in the Standard action library that is accessed through the process menu Long term planning > Settings. In the settings view select Standard Action Library
The Standard action can be removed from the library if it has not yet been used on the process side.
The first time the Standard action is used on the process side, the delete action is no longer available.
If you want to disable a Standard action that is already in use, you can define it Not in use.
On the left side of the standard action, select the three-dot icon, and click Edit
Clear the selection in the box Standard action in use, and then press Save
The Standard action is no longer visible on the process side of the drop-down menu. This means that it can no longer be added to an item. Pending Standard actions can be completed normally, but no new instances of that standard action will be created into future. User will get a notification about this in the interface.