Always make sure you backup your registry file before you make any changes.
Then, follow these steps:
STEP 1. Start Registry Editor
STEP 2. Locate and then click the following registry subkey:
STEP 3. On the Edit menu, click Modify, and then click Decimal
STEP 4. Type the new port number, and then click OK
STEP 5. Quit Registry Editor
STEP 6. Restart the computer
Note When you try to connect to this computer by using the Remote Desktop connection, you must type the new port. Maybe you have to set the firewall to allow the new port number before you connect to this computer by using the Remote Desktop connection.