In addition to tcash21's numeric indexing if OP may have been looking for negative indexing by name. Here's a few ways I know, some are risky than others to use:
mtcars[, -which(names(mtcars) == "carb")] #only works on a single column
mtcars[, names(mtcars) != "carb"] #only works on a single column
mtcars[, !names(mtcars) %in% c("carb", "mpg")]
mtcars[, -match(c("carb", "mpg"), names(mtcars))]
mtcars2 <- mtcars; mtcars2$hp <- NULL #lost column (risky)
library(gdata)
remove.vars(mtcars2, names=c("mpg", "carb"), info=TRUE)
Generally I use:
mtcars[, !names(mtcars) %in% c("carb", "mpg")]
because I feel it's safe and efficient.