When you extract a single row from a data frame you get a one-row data frame. Convert it to a numeric vector:
as.numeric(df[1,])
As @Roland suggests, unlist(df[1,]) will convert the one-row data frame to a numeric vector without dropping the names. Therefore unname(unlist(df[1,])) is another, slightly more explicit way to get to the same result.
As @Josh comments below, if you have a not-completely-numeric (alphabetic, factor, mixed …) data frame, you need as.character(df[1,]) instead.