If you would like to use Raspberry Pi as the gateway, please continue with this tutorial:
If you would like to use your extra Android phone as the gateway, please continue with this tutorial:
You can buy RuuviTag sensors from Ruuvi Shop with world-wide shipping.
You can remove a sensor with the gateway software.
If you have an Android gateway, long press the sensor item in the main view. The item background will turn to red. Tap the trash can icon in the top right corner.
If you have a Raspberry Pi gateway, stop the gateway and issue command
meazurem-gateway remove -address address_of_the_tag
You can remove a gateway with the client app.
Navigate to Account tab. Use the down caret icon in the gateway you want to remove to reveal the actions. Tap remove.