diff --git a/eslint/.eslintrc.js b/eslint/.eslintrc.js
index c2e1feebc..8b92bd262 100644
--- a/eslint/.eslintrc.js
+++ b/eslint/.eslintrc.js
@@ -59,7 +59,6 @@ module.exports = {
       'always'
     ],
     'bad-text': 2,
-    'no-extend': 0,// wait to turn this on until there are less usages, https://github.com/phetsims/phet-core/issues/71
 
     // Custom rule for checking the copyright.
     copyright: 2,
diff --git a/eslint/rules/no-extend.js b/eslint/rules/no-extend.js
deleted file mode 100644
index ad4ad28d3..000000000
--- a/eslint/rules/no-extend.js
+++ /dev/null
@@ -1,59 +0,0 @@
-// Copyright 2019, University of Colorado Boulder
-
-/**
- * Lint detector for invalid code based on its tokenized parts.
- * This rule is currently hard coded for _.extend, but could be easily adapted for any code tokens. Currently this will only
- * flag items that are in requirejs files (signified with a "define(" and then a "require" arg (see regex below).
- *
- * @author Michael Kauzmann (PhET Interactive Simulations)
- */
-
-/* eslint-env node */
-'use strict';
-
-module.exports = context => {
-
-  const badTextParts = [ '_', '.', 'extend' ];
-  return {
-    meta: {
-      fixable: 'code'
-    },
-    Program: node => {
-      const sourceCode = context.getSourceCode();
-      const codeTokens = sourceCode.getTokens( node );
-
-      for ( let i = 0; i < codeTokens.length; i++ ) {
-        const token = codeTokens[ i ]; // {Token}
-        const failedTokens = [];
-        for ( let j = 0; j < badTextParts.length; j++ ) {
-          const badTextToken = badTextParts[ j ];
-          const combinedIndex = i + j;
-          if ( combinedIndex < codeTokens.length && codeTokens[ combinedIndex ].value === badTextToken ) {
-            failedTokens.push( codeTokens[ combinedIndex ] );
-          }
-          else {
-            break;
-          }
-        }
-
-        // if they are the same
-        if ( failedTokens.map( token => token.value ).join( '' ) === badTextParts.join( '' ) && // if it matches
-             /^define\(.*require/m.test( sourceCode.text ) ) { // proxy for requirejs
-          context.report( {
-            loc: token.loc.start,
-            message: 'requirejs file contains _.extend, use merge instead',
-            fix: fixer => {
-
-              // This hard coded fixer is meant for replacing _.extend with merge, see https://github.com/phetsims/phet-core/issues/71
-              return fixer.replaceTextRange( [ failedTokens[ 0 ].start, failedTokens[ failedTokens.length - 1 ].end ], 'merge' );
-            }
-          } );
-        }
-      }
-    }
-  };
-};
-
-module.exports.schema = [
-  // JSON Schema for rule options goes here
-];
\ No newline at end of file