Indeed the volume looks like it is mounted. From the screenshot of your terminal, I think you're having some formatting issues with the command. For what it's worth, be careful with that rm command - it deletes things!
Let's break this down:
- After mounting the volume, launch Terminal
- You should see an empty bash prompt (in your case it is "-bash-3.2#"). There should be nothing after that.
- Type this exact string (without the quotes) "cd /Volumes/Macintosh\ HD/Library/Audio/Plug-Ins/HAL/"
- That will send you to the directory where the plugin lives
- Type "ls -al"
- This will give you a listing of the contents of the directory. You should see at least one listing for a Razer product.
- For each Razer listing you will type "rm FILENAME" where FILENAME is replaced with the name of the listing (case sensitive). Note that typing the first few characters of the name and hitting TAB will autocomplete the name. Clicking return will delete the listing unless it is a directory.
- If Terminal responds by saying that the listing is a directory, then type "rm -r FILENAME". This will delete the directory and its contents.
- Continue until all Razer listings are removed. At any time you can run the ls -al" command to see what remains.
Good luck!
Disclaimer: Deleting files from your computer is risky. Especially when using "rm -r" which is recursive. I do not take any responsibility for unintended consequences. You embark on this process at your own risk!