See FAQs for more information on Nemonic products.

Program error(Mobile)iOS - The “Delete This Device” button keeps displaying.

From your iPhone/iPad, if the “Delete This Device” keeps on displaying even if you click on it, 

go to Home > Settings > Bluetooth > Nemonic Printer previously connected. 

Tap the (i) icon next to it at the right. Tap “Delete This Device” to remove it from the device list. 

Then, try to reconnect it using the app.