How do you delete a spartan company, or at the least, how do you kick members?
I think that all members (including you) have to leave the company
You can disband a Company by visiting the Company profile, navigating to “Administration” and then choosing Disband. You will be prompted to confirm your gamertag as this is a destructive action: Stats will be wiped, taking Commendation progress with it, and your forum activity vanishes.
You can remove players from the Company by visiting their Company profile, navigating to “Administration” and then choosing “Manage Members.” You can block players by navigating to Blocked Users.
https://www.halowaypoint.com/en-us/community/spartan-companies/faq