This is a self-hosted install of an open-source client. There is no company behind it, no analytics and no third party receiving your data.
Nothing is stored about you on the server. Your game account belongs to the UO shard, which is separate software; this client only relays your connection to it.
Your browser keeps this shard's game files and your local client settings on your own machine. Clearing your browser's site data removes them.
Discord tells this install three things, and they are all that is kept:
Plus the time you were last seen, so an install can tell an abandoned account from an active one.
Once you sign in, the client can sync your settings so they follow you between computers. That is five files and the server rejects anything else:
macros.xml — your macrosgumps.xml — your window layoutinfobar.xml — your info barskillsgroups.xml — your skill groupingsprofile.json — your client optionsThey are the client's own configuration files. Nothing about your character, your gameplay or your conversations is in them, and none of that is stored here: it lives on the UO shard.
The delete button in your profile removes your identity, your settings and your synced profile files. It is immediate and cannot be undone.
It does not delete your character or your account on the UO shard — that is separate software with its own administrators. Ask them.
Whoever runs this install can also delete your stored data from their admin panel, and can see the same three fields Discord provided. They cannot see your password — this client never receives your shard password in a readable form on the server; it is relayed to the shard as part of the game protocol.
Like any web server, this one writes connection logs — address, time, what was requested. They exist to run the service and are not combined with anything above.
The person or group running this install. The client's authors host nothing and receive nothing. If your jurisdiction gives you rights over your data, they are the ones to ask.