How does Win8 system change the opening method of xml file to unknown file

After the XML document is opened with the default program, the default method is used each time it is opened. How to change the opening method of the xml file to an unknown file? The following is a small series to introduce how the Win8 system turns the xml file into an unknown file. .
1. First, we need to determine the SID number of the current account;
2. On the traditional desktop, press the Windows key plus the X key, then press the R key, then type regedit and press Enter. Confirm the SID number of each account in the following key values;
(HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionProfileList.)

3. Secondly, grab the key value through regshot, after the comparison, you can press the following operation to make it Unknown file.
4. If the xml file is opened by default as Notepad (other methods can be changed appropriately), you can try to delete the following registry file (Note: S-1-5-21-3452318729-4151646049-3877892598-1004 is current) The SID of the account, the SID number of the different account is different):
(HKUS-1-5-21-3452318729-4151646049-3877892598-1004SoftwareMicrosoftWindowsCurrentVersionExplorerFileExts.xml)
(HKUS-1-5-21-3452318729-4151646049- 3877892598-1004SoftwareMicrosoftWindowsRoamingOpenWithFileExts.XML)
(HKUS-1-5-21-3452318729-4151646049-3877892598-1004SoftwareMicrosoftWindowsCurrentVersionApplicationAssociationToastsApplicationsNOTEPAD.EXE_.XML: 0x00000000)
5. After deleting the above three key values, the file will be again Becomes an unknown file.