You can control when to display or hide your presentation's joining instructions. This can be done for both the QR code and the numeric code.
Hide the instructions before you start presenting
Select the slide where you want to hide the instructions in the edit view
Open the Edit tab by selecting the whole slide on the slide canvas
Toggle the options under the Join Instructions heading: 'Display QR code' and/or 'Display instructions bar'
These options control the QR code displayed on the right side and the code displayed at the top of the slide:
Hide the joining instructions while presenting
While presenting you can use the 'i' hotkey to quickly show or hide the QR code.
You can also control this using the Mentimote:
Open the Mentimote (Pro feature)
Toggle “Show access code” under the "Joining Instructions" heading
If you want to send out the joining instructions in advance instead or want your audience to connect with the presentation in another way, hiding the instructions can be a useful feature to avoid redundant information.