You can do the following:
- Go to Edit> Project Settings> Engine Input> Mobile> Default Touch Interface and make it to None
- In your Blueprint script:
- When you want to show the touch interface, you can use Activate Touch Interface "YourtouchInterfaceName"
- When you want to hide the touch interface, you can use Activate Touch Interface "None"
- Be sure to link the Activate Touch Interface to the correct player Controller by using Get Player Controller and the correct Controller ID