How do i get rid of the black box that appears when i start a text on my phone?

If you're using a 3rd party app to send messages, please contact that 3rd party app developer/support team and ask them.

If you're using Apple Message or iMessage app, please take a screenshot of your screen (using these instructions:--> Take a screenshot on your iPhone ) and post it here, showing us that black box.

Thanks

Giulio