How should I use 3.3V + 5V in KiCad without getting an ERC error?

Below are parts of my design.

Using KiCad, I have problems using both VCC (5V) and 3.3V power, both from Arduino Mega pins.

If on U6 (flash) I connect 3 and 7 I get a similar error, so I guess I did something wrong regarding the PWR_FLAG settings. I also tried using the VCCQ (it also has a round symbol like VCC), but then I get different errors.

What should I change in my schematics to use both 3.3V and 5V without any ERC errors?

If you're absolutely positively never going to use those pins as I/O, then copy that part into a new library part and define the pins as inputs. It's probably safer, if you have the room, to pull those pins up through resistors (10k$$\\Omega\$$ is a nice round number). That way if someone messes up the software and sets the pins to I/O they'll just harmlessly pull their outputs low, at the cost of some supply current.