Step 2 in the tutorial below can help show you how to. You might print it out or write it down first to have it as a reference if needed. The link in step 2A will show you how to open a command prompt at boot.
The main thing is to make sure that you use the correct drive letter/volume number for the drive/partition that your Windows 7 is installed on.
Once you know that, you would just use that drive letter in the path of the folder in the command. For example, if the drive letter is C
at boot, then you would type this command. RD /S /Q "C:\Users\ralobban" Folder - Delete from Command Prompt
If you have any questions, then please feel free to ask.