Upgrade using ArchLinux

Are there any documents, tutorials, or something related to upgrading when Ghost is installed on an ArchLinux instance?
If I try to upgrade from command line running “ghost update” using the ghost user, who owns the /opt/ghost directory, I get the “You can’t run commands with the “ghost” user. Switch to your own user and try again”, but if I use other user, a sudoer one, I get the “Your user does not own the directory /opt/ghost and is also not a member of the owning group” message…I need to update the version, but don’t know how to deal with this situation.
Any help will be very appreciated!
Thanks in advance, and best regards,