# Remove third column - by column number
MyMatrix <- MyMatrix[,-3]
# Remove third and fifth columns - by feeding the matrix a boolean vector
MyMatrix <- MyMatrix[,c(TRUE,TRUE,FALSE,TRUE,FALSE,TRUE)]
DT[, coltodelete := NULL]
# delete multiple columns in r
# delete column in R by mapping Null value to them
dataset$firstcol <- dataset$nextcol <- dataset$anothercol <- NULL
keeps <- c("y", "a")
DF[keeps]
DataNAME$ColumnNAME <- NULL