In order to change the owner of a data template, click on the checkbox to left of the data template name and click Change Owner. Upon click of the Change Owner link a popup will appear that shows all of the users to whom you can assign the selected locator to. Once you select a user from the dropdown presented and confirm, that user will become the new owner of the locator. Only the owner of the locator and the Admin user can perform this.
You can alternatively get to the data template edit screen and then select a user from the Owner dropdown presented below and hit Save.