This will hide your balance when in "Receive" mode: https://github.com/monero-project/monero-gui/issues/925 It will be included in the next release. You can also build the GUI yourself and already use the feature today.
Hiding balance in Monero GUI client
btcxyzzz posted this 6 years ago
Just as subject says, there should be an option to hide the display of balance. It's pretty self-explanatory and fundamental.