Check if username to remove is valid

src/freedombone-installer

@@ -1229,15 +1229,17 @@ function add_remove_users {
             if [ ${#remove_username} -le 32 ]; then
                 if valid_username_characters "$remove_username"; then
                     if [ -d "/home/$remove_username" ]; then
-                        admin_username=$(grep 'MY_USERNAME=' "$CONFIGURATION_FILE" | head -n 1 | awk -F '=' '{print $2}')
-                        if [[ "$remove_username" != "$admin_username" ]]; then
-                            check_for_existing_processes $remove_user_script
-                            { echo "/usr/local/bin/${PROJECT_NAME}-rmuser $remove_username > $webadmin_install_dir/log.txt";
-                              echo "exit 0"; } >> $remove_user_script
-                            chmod +x $remove_user_script
-
-                            # run in a separate process
-                            ./$remove_user_script &
+                        if [[ $(is_valid_user "$remove_username") == "1" ]]; then
+                            admin_username=$(grep 'MY_USERNAME=' "$CONFIGURATION_FILE" | head -n 1 | awk -F '=' '{print $2}')
+                            if [[ "$remove_username" != "$admin_username" ]]; then
+                                check_for_existing_processes $remove_user_script
+                                { echo "/usr/local/bin/${PROJECT_NAME}-rmuser $remove_username > $webadmin_install_dir/log.txt";
+                                  echo "exit 0"; } >> $remove_user_script
+                                chmod +x $remove_user_script
+
+                                # run in a separate process
+                                ./$remove_user_script &
+                            fi
                         fi
                     fi
                 fi