I dont know how to delete my xbox 360 profile

You may have a corrupted profile. To resolve this, delete the profile that's stored on your Xbox 360 console, clear the system cache, and then download your profile again.

"The email address or password you entered is not valid" error ...

https://support.xbox.com > my-account > manage-account

Error 80151103 occurs when you download your profile to ...

https://support.xbox.com > help > errors > xbox-360
There's a problem with the security information for your Microsoft account. There's a problem with the Xbox Live profile that's stored on your Xbox 360 console.

This site may help you.
http://support.xbox.com/en-US/xbox-360/settings-and-initial-setup/profile-move-delete

NHL 08 for the 360 doesn't ask for a code when you put in the game. I'm presuming it's asking for the code to your gamertag. Enter this code or choose a different gamertag. If you don't know the code, you can select another gamertag (or create a new one) or delete the profile but if you want to keep your save files just choose delete profile (rather than delete profile and everything else).

You can recover this profile later if you have the ID and password (there's a recover gamertag option in the dashboard [press the big X button]).

If you want to delete the profile, go to my xbox then system settings
select memory then all devices
select gamer profiles and select the one you want and then select delete then delete profile only

i had this happen myself, its just how your xbox uses your profile, with the new usb stick, the way to solve the issue is to delete both profiles off the hdd and usb. then recover your gamertag from xbox live. that will fix issue

Unfortunately this is the only way to recover your profile. You may try calling 1-800-4myxbox and see if they can assist you.

If the profile that is deleted was an Xbox live profile, then that profile can recovered through Xbox live.
However there is no way to recover anything else stored on the Xbox console that includes any offline profiles and game saves.

call 1 800 4 my xbox they can help you recover your gamertag.

you cant recover the saves only the profile

good luck i getting your problem solved with an attitude like that you certainly don't need our help. The problem was clearly too hard for you....

I have heared that if you just delete the profile, just the profile, everything will be just fine (note: This only works if your profile is on xbox live).
Just go to memor, then go into the saving device the corrupted profile is on. Then "click" on the botton that says profile and delete the corrupted profile. Remember; the profile will be a small save and not taking up most of your harddrive, look for something with MB size, not GB size. When you have done this, go to "recover gamertag" and do so for the profile you just deleted. After all this, your game saves and achivements should be present and working.