How to remove NA (data with missing values) in geom_col?

Try this:

data3 %>%
  drop_na() %>%   # add this line
  arrange(Dif_GAD7_0_9) %>%
  ...

DEMO

If you have this tibble:

library(tidyverse)

mydf <- tibble(
  names = c(LETTERS[1:4], NA_character_, "F", "G", NA_character_),
  val = c(NA_real_, 2, 3, NA_real_, 5, 6, NA_real_, 8)
)

and you use drop_na() the result will be

But if you want to remove NA only from some column, you can use drop_na(names)

Or drop_na(val)