Canon EOS 5D MARK IV Instruction Manual page 623

Since the nickname is a required wireless setting, you cannot delete all the
characters.
Enter a nickname.
4
For instructions on entering

characters, see the next page.
When using the default nickname (the

camera name), proceed to step 5.
Otherwise, enter any characters

between 1 to 10 characters in length.
Exit the setting.
5
When you are finished, press the

<M> button.
Select [OK] on the confirmation

dialog and press <0> to return to
the menu screen.
Registering a Nickname
W-9