Changing the Password of Internal HD Mounted As An External Drive

[thenateo]

Hi there. My friend just spilled water on his computer and upon restarting, we found that the shift key was internally stuck. It wouldn't let him input the password correctly because it was acting as if the shift key was pressed (even though it wasn't). I'm assuming this was just caused by some sort of water damage. I'm not sure how to remedy that situation.

So I removed his HD and plugged it in to my iMac as an external drive. I've done this before to salvage files from my old Macbook when I had water damage as well. However, I'm not sure how to change or remove the password with the HD plugged in as an external drive on my computer. Any ideas?

Thanks!