r kable change with of the table code example

Example 1: options kable NA

options(knitr.kable.NA = '')

Example 2: kable column names

require(knitr)

df <- data.frame(A=c(1,2),B=c(4,2),C=c(3,4),D=c(8,7))
knitr::kable(df, 
             col.names = c("Space in name",
                           "(Special Characters)",
                           "$\\delta{m}_1$",
                           "Space in name"))