Sharky

How does one remove a previously uploaded resource pack from the server via the GUI, since the properties file cannot be directly edited?

That's the one, enter the uploaded world name and save. Restart server

Use Essentials, then assign perms to players/groups

The use Invision Community, link at bottom of forum page.

This was changed a little while ago: 27 June 2019. See news link:

Manage whitelist from Dashboard, run command via console. I assume you are not running any permission plugin? Or temp Op yourself via console and run command in game.