If ou want to drop rows that have an NA value, you can use the drop_na function from the tidyr package.
DF <- data.frame(A=c(1,NA,3,4,5),
B=c(1,2,3,NA,5),
C=c(1,2,NA,4,5))
DF
A B C
1 1 1 1
2 NA 2 2
3 3 3 NA
4 4 NA 4
5 5 5 5
library(tidyr)
DFclean <- drop_na(DF)
DFclean
A B C
1 1 1 1
2 5 5 5