package main

import (
    "fmt"
    "strings"
)

func main() {
    s := "t Hello, Worldn "
    fmt.Printf("%d %qn", len(s), s)
    t := strings.TrimSpace(s)
    fmt.Printf("%d %qn", len(t), t)
}

16 "t Hello, Worldn "
12 "Hello, World"

fmt.Printf("[%q]", strings.Trim(" Achtung  ", " "))