Updating existing website remotely?

Hello everyone,

My Brazilian Jiu Jitsu coach has a website in need of some updates and functionality fixes. I was wondering how I go about getting remote access into the website and updating it from my computer at home? He is all for this but is not very tech savvy. Can I work on his website remotely or do I have to go to his place and work on it from his computer? I know I would need an admin password and that sort of thing but I could not find anyway to get to admin controls from his site https://texaselitemma.com Any help or advice on the site would be appreciated.

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