Summarize:

You'll need to be on an account that has administrator privileges in order to make changes to your computer's registry. Click the Windows logo in the bottom-left corner of the screen. This will search your computer for the Registry Editor command. It's a teal collection of blocks at the top of the Start window. Doing so will open the Registry Editor window. To do so:  Expand the HKEY_LOCAL_MACHINE folder by double-clicking it. Expand SOFTWARE  Scroll down and expand Microsoft  Scroll down and expand Windows NT  Expand CurrentVersion  Expand Software Protection Platform  Click Activation﻿ It's a blue-and-white icon on the right side of the window. A drop-down menu will appear.  If your mouse doesn't have a right-click button, click the right side of the mouse, or use two fingers to click the mouse. If your computer uses a trackpad instead of a mouse, use two fingers to tap the trackpad or press the bottom-right side of the trackpad. It's at the top of the drop-down menu. A window will appear. In the "Value data" text box, replace the "0" with a "1", then click OK. You may be prompted to confirm this choice. If so, click Yes or OK before proceeding. This item is also on the right side of the page.  This will prevent the activation notification from appearing on your desktop. While removing the watermark notification will work temporarily, you may need to disable it again in the future.
Make sure that you're on an administrator account. Open Start . Type in regedit. Click regedit. Click Yes when prompted. Go to the "Activation" key. Right-click Manual. Click Modify. Change the value data. Right-click NotificationDisabled. Click Modify. Change the value data to 1. Repeat this process if the notification reappears.