On the workspace, tap on the card with the « + »;

Tap on the button with the cloud icon;

Tap on Decommission;

Select the form within the list of your current forms available in Paperless you want to remove from your available templates;
Tap on Decommission;

Enter your session's password to confirm the action to remove the template;

Tap on Accept.

The template of your form will be removed from the list of forms ready for production (in the "+" card) and you won't be able to create a new form with that template anymore.
The scheduled forms (tasks) will still be there until you stop their recurrence.