Step 1 click start type command prompt then left click the command prompt and choose run as administrator.
Step 2 from the DOS window you want to type the following
Net user guest *
You may press the enter key then
Type a password for the user: here you may type your password
Retype the password to confirm: re enter the password
The command completed successfully.
Now your guest account password has been set.
In feature you want to remove your password you have to follow the same command and press the enter key two times.