Deleting Reg Key

Hello Hole, and welcome to Seven Forums. :)

What registry key are you trying to delete?

You do not want to just delete a registry key unless you know what it is for. Doing so could leave you reinstalling Windows 7.

Have you also set permissions for the key to "Allow" your account "Full control" of it before trying to delete it? Step 3 in OPTION THREE of the tutorial below can help show you more on this for now if needed.

Take Ownership of file

You may just need to also set permissions for it as well before being able to delete it.

Did you already set permissions?

Could you post a screenshot showing the full error message you got, the registry key, and the permission and ownership settings for the registry key to see if this may help?

Screenshots and Files - Upload and Post in Seven Forums

The key is in the HKLM branch. You need to invoke the registry editor as an administrator. Even though you're an administrator, running regedit (or indeed any other program) as normal means that it is running under your standard user token (Administrators have 2 modus operandii - standard and elevated). You need to right-click on the program (in this case, regedit) and choose Run as administrator.