added delete method (based on numbered list)

src/methods/delete.js

@@ -0,0 +1,29 @@
+const {exec} = require("child_process");
+const {promisify} = require("util");
+const promisifiedExec = promisify(exec);
+
+/**
+  * Delete ufw rule(s). (root/sudo access is mandatory)
+  * @param {number} num Number of the rules list. The first rule starts from number 1.
+  * @returns {Promise<Boolean>} Returns a boolean.
+*/
+module.exports = async function(num) {
+  try {
+    if (!num) throw new Error("Missing num input.");
+    if (typeof num !== "number") throw new Error("The num must be type of number.");
+    if (num === 0) num = 1;
+
+    let res = await promisifiedExec(`echo "y" | sudo ufw delete ${num}`);
+
+    if (res.stderr) throw new Error(res.stderr);
+
+    if (res.stdout) {
+      return true;
+    } else {
+      console.log(res.stdout);
+      return false;
+    };
+  } catch (err) {
+    throw new Error(err);
+  };
+};