HOW CAN I BYPASS ACTIVATION LOCK ON IPHONE6 OR RESET TO FACTORY

The easiest way is to resort to iTunes. You can follow below steps to do that.

iTunes enables you to restore iPhone 6 Plus to factory settings. Before you start restoring iPhone to factory settings, please note that you need to install the latest version of iTunes on your PC or MAC. Then go to Settings > iCloud to turn off Find My iPhone. Now, you can factory reset your iPhone 6 Plus with iTunes as follows.
1. Plug iPhone 6 Plus into the computer with the USB cable. The iTunes on your computer will automatically launch. If not, double-click the icon to start it.
2. Click the name of your iPhone 6 Plus at the upper right corner of iTunes, and then the information of your iPhone 6 Plus will be shown. Click the "Restore iPhone" button in the window to start.
3. iTunes will ask whether you want to back up iPhone 6 Plus before restoring. You'd better choose "Yes" for the reset will erase the contents in your iPhone 6 Plus. Then iTunes will start restoring your iPhone 6 Plus to factory settings.

3. Click Restore again to confirm. Then iTunes erases your iPhone 6 Plus and installs the latest iOS software. After you restore your iPhone 6 Plus to factory settings, it will restart. Now you can set it up as new.

For more methods, check: How to Restore iPhone 6 Plus to Factory Settings

Check youtube.