On Signitic, you can delegate part or all of the administration of your account to users.
To appoint a new administrator, go to the modification page of the very user. Then scroll through the selection of the different roles and choose the one appropriate for the user:
To see how to create new roles, please check this article.
Once the role is selected, don't forget to save!
An email will be sent to the user indicating the creation of his account only if he was not administrator before the change.