Hide dependent NA in bar chart

[Ashley-Stevens]

With a multivariate dataset there are NA values present which differ depending on factor variables chosen - we can't exclude every NA in dataset but would like to exclude NA'S from the bar chart depending on the variables that are chosen.

For example, in this image we can see the N/A column. Is this possible to exclude and I haven't found the documentation, or if not, what changes should I make to exclude the NA columns (or rows) in the bar chart?