If you are in the process of erasing all traces of a program from your computer or are attempting to manually remove viruses or adware, use the Registry Editor utility to access the HKLM/Software section of the Windows 8 Registry. The Registry is a database used by Windows to store its settings and options. Most programs you install on your computer create keys in the HKEY_LOCAL_MACHINE/Software section of the Registry. These keys contain configuration settings, paths to various files and even uninstall information. When you uninstall programs, their keys might not be removed from the Software section. Note that deleting entries from the Windows Registry is dangerous; you may cause programs to malfunction and even crash the entire operating system.
Press "Windows-R" to display the Run dialog box. Type "regedit.exe" (without the quotes) into the Run field and then press "Enter" to open the Registry Editor. Using the Registry Editor, you can browse through the Windows Registry and delete keys or modify values.
Double-click "Computer" to expand it and display its keys. Double-click the "HKEY_LOCAL_MACHINE" key to expand it and then double-click the "Software" key to expand it. Most programs create their registry entries in this section. The keys are named after the software manufacturer -- Adobe or Microsoft, for example.
Select any of the keys and press "Delete" if you want to erase it. Click "Yes" to confirm and permanently delete the key from the Registry. Double-clicking one of the keys expands it and reveals additional sub-keys and values.
If you can't access the Windows Registry or Windows prevents you from deleting keys or values, log in as an administrator. In most cases, only the administrator can modify the Registry.
Back up the key that you want to delete, in case you make a mistake and need to recover it later. To back up a key, right-click it and choose "Export" from the context menu. Type a name into the "File name" field, select the destination folder and then click "Save" to save the key.
Values are displayed in the right pane, after you select a key or sub-key from the left pane. To view additional sub-keys, double-click any of the keys in the Registry. Keys that contain sub-keys have a small, white arrowhead to the left of the name.
If you double-click a key in the HKLM/Software section, you can see the programs installed by that specific manufacturer on your Windows 8 PC.
To modify a value, double-click the value in the right pane, and then edit the "Value data" field. Click "OK" to save the changes.
To create a new value, select the key in the left pane, right-click in the right pane, select "New" and then select the value type. Type a name for the value and press "Enter" to save it. To modify its data, double-click it and edit the "Value data" field.
Many programs also create entries in the HKEY_CURRENT_USER\Software section of the Registry.
Changes you make to the Windows Registry take effect immediately after you click "Yes" to confirm a deletion or click "OK" to confirm a value change. You can't undo the changes.
Deleting a wrong key may cause your entire Windows 8 operating system to crash. Also, changing a wrong value can cause an entire software suite to crash. In this case you may need to repair or even reinstall the program. Even if you backed up the key you are about to delete, you may not be able to restore it if Windows is no longer able to boot.