diff --git a/src/core/operations/A1Z26CipherDecode.mjs b/src/core/operations/A1Z26CipherDecode.mjs
deleted file mode 100644
index 0b113945..00000000
--- a/src/core/operations/A1Z26CipherDecode.mjs
+++ /dev/null
@@ -1,63 +0,0 @@
-/**
- * @author Jarmo van Lenthe [github.com/jarmovanlenthe]
- * @copyright Crown Copyright 2018
- * @license Apache-2.0
- */
-
-import Operation from "../Operation.mjs";
-import Utils from "../Utils.mjs";
-import {DELIM_OPTIONS} from "../lib/Delim.mjs";
-import OperationError from "../errors/OperationError.mjs";
-
-/**
- * A1Z26 Cipher Decode operation
- */
-class A1Z26CipherDecode extends Operation {
-
-    /**
-     * A1Z26CipherDecode constructor
-     */
-    constructor() {
-        super();
-
-        this.name = "A1Z26 Cipher Decode";
-        this.module = "Ciphers";
-        this.description = "Converts alphabet order numbers into their corresponding  alphabet character.<br><br>e.g. <code>1</code> becomes <code>a</code> and <code>2</code> becomes <code>b</code>.";
-        this.infoURL = "";
-        this.inputType = "string";
-        this.outputType = "string";
-        this.args = [
-            {
-                name: "Delimiter",
-                type: "option",
-                value: DELIM_OPTIONS
-            }
-        ];
-    }
-
-    /**
-     * @param {string} input
-     * @param {Object[]} args
-     * @returns {string}
-     */
-    run(input, args) {
-        const delim = Utils.charRep(args[0] || "Space");
-
-        if (input.length === 0) {
-            return [];
-        }
-
-        const bites = input.split(delim);
-        let latin1 = "";
-        for (let i = 0; i < bites.length; i++) {
-            if (bites[i] < 1 || bites[i] > 26) {
-                throw new OperationError("Error: all numbers must be between 1 and 26.");
-            }
-            latin1 += Utils.chr(parseInt(bites[i], 10) + 96);
-        }
-        return latin1;
-    }
-
-}
-
-export default A1Z26CipherDecode;